34322 Federal Register / Vol. 65, No. 103 / Friday, May 26, 2000 / Rules and Regulations

DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 99–NM–161–AD; Amendment

39–11749; AD 2000–11–01]

RIN 2120–AA64

Airworthiness Directives; McDonnell

Douglas Model DC–9–80 and MD–90–

30 Series Airplanes, and Model MD–88

Airplanes

AGENCY: Federal Aviation

Administration, DOT.

ACTION: Final rule.

SUMMARY: This amendment adopts a

new airworthiness directive (AD),

applicable to certain McDonnell

Douglas Model DC–9–80 and MD–90–30

series airplanes, and Model MD–88

airplanes, that requires a determination

be made of whether, and at what

locations, metallized

polyethyleneteraphthalate (MPET)

insulation blankets are installed, and

replacement of MPET insulation

blankets with new insulation blankets.

This amendment is prompted by reports

of in-flight and ground fires on certain

airplanes manufactured with insulation

blankets covered with MPET, which

may contribute to the spread of a fire

when ignition occurs from small

ignition sources such as electrical arcing

or sparking. The actions specified by

this AD are intended to ensure that

insulation blankets constructed of

MPET are removed from the fuselage.

Such insulation blankets could

propagate a small fire that is the result

of an otherwise harmless electrical arc

and could lead to a much larger fire.

DATES: Effective June 30, 2000.

The incorporation by reference of

certain publications listed in the

regulations is approved by the Director

of the Federal Register as of June 30,

2000.

ADDRESSES: The service information

referenced in this AD may be obtained

from Boeing Commercial Aircraft

Group, Long Beach Division, 3855

Lakewood Boulevard, Long Beach,

California 90846, Attention: Technical

Publications Business Administration,

Dept. C1–L51 (2–60). This information

may be examined at the Federal

Aviation Administration (FAA),

Transport Airplane Directorate, Rules

Docket, 1601 Lind Avenue, SW.,

Renton, Washington; or at the FAA,

Transport Airplane Directorate, Los

Angeles Aircraft Certification Office,

3960 Paramount Boulevard, Lakewood,

California; or at the Office of the Federal

Register, 800 North Capitol Street, NW.,

suite 700, Washington, DC.

FOR FURTHER INFORMATION CONTACT:

Robert Stacho, Aerospace Engineer,

Systems and Equipment Branch, ANM–

130L, FAA, Transport Airplane

Directorate, Los Angeles Aircraft

Certification Office, 3960 Paramount

Boulevard, Lakewood, California

90712–4137; telephone (562) 627–5334;

fax (562) 627–5210.

SUPPLEMENTARY INFORMATION: A

proposal to amend part 39 of the Federal

Aviation Regulations (14 CFR part 39) to

include an airworthiness directive (AD)

that is applicable to certain McDonnell

Douglas Model DC–9–80 and MD–90–30

series airplanes, and Model MD–88

airplanes was published as a notice of

proposed rulemaking (NPRM) in the

Federal Register on August 12, 1999 (64

FR 43966). A second proposal that was

identical to the NPRM, except that it

affected additional airplanes, was

published as a supplemental NPRM on

November 17, 1999 (64 FR 62613).

Those actions proposed to require that

a determination be made of whether,

and at what locations, metallized

polyethyleneteraphthalate (MPET)

insulation blankets are installed, and

replacement of MPET insulation

blankets with new insulation blankets.

Since the issuance of those NPRM’s,

the FAA has observed several

prototyping exercises that involved the

removal and replacement of MPET

insulation blankets. The information

obtained from these exercises assisted

the FAA, operators, and manufacturer in

understanding the technical details and

impact of the requirements of this AD.

Certain aspects of these prototype

exercises will be discussed in the FAA’s

response to the comments received from

the NPRM’s.

Comments

Interested persons have been afforded

an opportunity to participate in the

making of this amendment. Due

consideration has been given to the

comments received.

The FAA has received comments in

response to the NPRM’s and

supplemental NPRM’s to Rules Docket

No.’s. 99–NM–161–AD [applicable to

certain McDonnell Douglas Model DC–

9–81 (MD–81), DC–9–82 (MD–82), DC–

9–83 (MD–83), DC–9–87 (MD–87) series

airplanes; Model MD–90–30 series

airplanes; and Model MD–88 airplanes]

and 99–NM–162—AD (applicable to

certain McDonnell Douglas Model DC–

10–30 and –30F series airplanes, and

Model MD–11 and –11F series

airplanes). Because in most cases the

issues raised by the commenters are

generally relevant to both NPRM’s, each

final rule includes a discussion of all

comments received.

Support for Proposed AD’s

Several commenters support the

intent of the proposed AD’s; however,

they request that some changes be made

(discussed later).

Unsafe Condition

One commenter states that, because

the MPET insulation blankets only

propagate the flame and are not the

source of the flame, the proposed AD’s

should address the unsafe condition

(i.e., source of the flame) rather than

previously certified material (which met

the flammability standard at one time)

that is not creating the unsafe condition.

The FAA does not concur. MPET

insulation blankets, when ignited from

a small ignition source, such as an

electrical arc, can contribute to the

spread of a fire. Such insulation

blankets could propagate a small fire

and lead to a much larger fire. Potential

ignition sources exist in many areas of

the affected airplanes. It is extremely

difficult to determine where all

potential ignition sources are. To

provide the level of safety that is

expected by the public for transport

category airplanes, insulation blankets

constructed of MPET must be removed.

Therefore, the FAA finds that it has

properly identified the unsafe condition

(i.e., insulation blankets constructed of

MPET) addressed by these AD’s.

The same commenter suggests that the

subject blankets be handled as ‘‘attrition

replacements,’’ as intended in the

original McDonnell Douglas service

bulletins. The commenter states that,

since cabin interior flammability has

been addressed already to a large extent

by the FAA, MPET insulation blankets

could be treated comparably, and thus,

integrated into the overall interior

materials requirements. (The FAA infers

that the commenter is referring to the

provisions in 14 CFR section 121.312

related to ‘‘substantially complete

replacement of the cabin interior.’’)

These requirements not only mandate

stricter new standards, but allow older

airplane interiors to remain in service

until a balanced decision is made to

fully reconfigure the cabin. After that

decision is made, the entire

flammability rule must be met on these

older airplane interiors, as well. The

commenter argues that insulation

blankets could be included, since the

proposed requirements are in the same

category of ‘‘new flammability

standards’’ and do not address the

actual ignition source.

Federal Register / Vol. 65, No. 103 / Friday, May 26, 2000 / Rules and Regulations 34323

The FAA does not concur with the

commenter’s request to handle the

subject blankets as ‘‘attrition

replacements.’’ Attrition is appropriate

for safety enhancements, not to correct

identified unsafe conditions. There is a

distinct difference between correcting

an identified unsafe condition and

enhancing safety. The intent of the

interior material flammability

enhancement was to provide occupants

more time to evacuate an airplane before

the cabin environment would become

unsurvivable due to smoke and fire. The

existing interior materials were not

deemed unsafe, and therefore, could

remain in service until the airlines

needed to replacement them. With this

action, as discussed above, the FAA

finds that MPET-covered insulation

material represents an unsafe condition

that must be corrected. These AD’s are

a vehicle for ensuring that all affected

operators perform the necessary actions

that will address the identified unsafe

condition. Therefore, these AD’s are

appropriate and warranted.

One commenter expresses concern

that, because the requirements of the

proposed AD’s are extremely costly and

cumbersome, resources are being taken

away from more effective measures for

improving aviation safety. The

commenter states that there are safety

groups (both with wide aviation

business basis) that have targeted the

most important/critical areas to be

addressed. However, neither of these

groups has fire on board as its top

priority. The commenter interprets this

to mean that the safety experts looking

at statistical data would rather

concentrate their efforts in other fields.

While there may be groups that

concentrate their efforts in other areas,

the FAA has identified an unsafe

condition that needs to be corrected (as

discussed above). The activity referred

to is primarily aimed at identifying

areas for improved safety, and focusing

resources on the most effective

candidates. This is distinctly different

from correcting an identified unsafe

condition. Therefore, these AD’s are

appropriate and warranted.

One commenter notes that in its

experience most blankets are wet or

soaking wet in a short time after coming

out fairly dry (i.e., after extensive

drying) during a heavy check. The

commenter asks how it should explain

to its mechanics that they have to

replace wet blankets because of a fire

hazard.

The FAA infers from this comment

that the wet blankets are a result of the

atmospheric conditions in which the

airplane is being operated or a result of

moisture accumulation in the belly of

the fuselage. As discussed above, the

FAA has identified an unsafe condition

on the affected airplanes that needs to

be corrected. As addressed in the

preambles of the NPRM’s, the FAA has

received reports of a number of in-flight

and ground fires on in-service airplanes

manufactured with insulation blankets

covered with MPET, which can cause

fire to spread from a small ignition

source such as electrical arcing or

sparking. The fact that insulation

material itself may be wet may not

prevent the MPET film material from

propagating the fire to other

combustible materials and causing a

larger fire.

One commenter states that the

wording ‘‘otherwise harmless electrical

arcs’’ in the Summary section in the

preamble of the proposed AD’s is

misleading and requests that this

wording be removed. The commenter

reports that there has never been any

Maintenance Steering Group (MSG) 3

testing on airplane wiring, and that no

one other than the FAA has even

evaluated the problems associated with

momentary metal-to-metal contact of

wires. In addition, the FAA has never

evaluated the effects of spurious signals

emitted from degraded wires that can

affect flight control surfaces, autopilots,

rudders, etc.

The FAA does not concur with the

commenter’s request to revise the

Summary section of the AD’s. The term

‘‘otherwise harmless arcs’’ refers to an

electrical arc that, on insulation films

other than MPET, would not propagate

a fire. In this case, the effect of the arc

is negligible. In the case of MPET, an

uncontrolled fire could develop. The

FAA points out that these AD’s do not

address the aging wiring issues that can

affect various systems. As discussed in

the preamble of the NPRM’s, the FAA is

continuing to investigate various wiring

problems on certain airplanes. In

addition, the Aging System Task Force

(ASTF) is continuing to investigate the

need for specific aging wiring

inspections and tests, as well as the

potential effect on systems from

degraded wiring. The actions required

by this AD only address the identified

unsafe condition (i.e., insulation

blankets constructed of MPET). The

FAA may consider additional

rulemaking actions to address any other

identified unsafe condition.

Risk Assessment

Several commenters state that, in

concert with the scheduled prototyping,

a thorough risk assessment should be

accomplished, particularly on the

effects of replacing insulation blankets

on the electrical (including wiring,

cables, and installations), hydraulic, and

mechanical systems. One commenter

states that the risk assessment must be

taken into account when mandating the

scope and compliance of the proposed

AD’s. Several commenters state that a

risk assessment is needed to determine

whether areas exist where the risks

associated with the replacement of

MPET insulation blankets outweigh the

benefits of replacing them. Risks

inherent with disturbing airplane wiring

and other permanently installed

systems, particularly on the scale

contemplated by the proposed AD’s, are

of primary concern. This and other

related risks should be addressed using

a structured method that considers the

characteristics of MPET and alternative

films, design and operation of overlying

systems, susceptibility of those systems

to damage during the replacement of

insulation under proposed methods,

and likely effects of any damage to those

systems. One commenter states that the

proposed AD’s are not supported by

such an analysis.

The FAA does not concur that a

formal risk assessment is necessary. If

accomplished properly, the replacement

required by this AD will not disrupt

wiring in such a way as to adversely

affect safety. Generally, the prototype

exercises demonstrated that the required

replacement can be accomplished

safely. In addition, Boeing is revising

the referenced service bulletins to

provide additional guidance on

techniques to ensure safe replacements.

The primary reason for providing an

extended compliance time for this AD,

as discussed under the next heading, is

to ensure that operators have adequate

time to accomplish the replacements

properly. On the other hand, MPET

insulation blankets have been shown to

create an unsafe condition that must be

corrected. Furthermore, the FAA will

require any operator/modifier that

develops its own installation data to

include specific instructions to ensure

that any displaced wires, systems, and

installations are in an airworthy

condition after accomplishment of the

required replacement. The FAA will

monitor these areas of concern during

the accomplishment of the insulation

blanket installations. Finally, if

operators can show that removal and

replacement of MPET insulation

blankets in certain areas of an airplane

will create a greater risk of an unsafe

condition than leaving the MPET

blankets in place, the FAA will consider

requests that provide an acceptable level

of safety under the provision of

paragraph (e) of the final rule. Any

request to leave MPET insulation

34324 Federal Register / Vol. 65, No. 103 / Friday, May 26, 2000 / Rules and Regulations

blankets installed in an airplane must

provide justification that the identified

unsafe condition has been minimized

and that an acceptable level of safety is

maintained.

One commenter states that the

proposed AD’s should be rewritten to

limit the blanket replacement to areas of

high risk, or conversely, retain existing

blankets in areas with no wiring or with

wiring deemed to pose little or no

hazard.

The FAA does not concur. No

technical justification, criteria, or data

were submitted to support the

commenter’s request. Potential ignition

sources exist throughout the airplane

and insulation blankets constructed of

MPET film material are located

throughout the airplane. It is, therefore,

extremely difficult to identify high risk

areas and areas of little or no risk. The

FAA finds that MPET insulation

blankets in all areas of the affected

airplanes must be addressed.

One commenter states that the

requirements of the proposed AD’s

should be recast into phases so as to

first respond across the worldwide fleet

of affected airplanes to the areas of

highest perceived risk. Thereafter, the

areas of lesser perceived risk can be

dealt with at a more appropriate pace.

Targeting the highest perceived risk

areas of the worldwide fleet of affected

airplanes first would provide the

greatest decrease in risk across the fleet

most quickly. This approach also would

make the best use of limited resources,

lessen the substantial adverse impact to

the traveling public of excessive fleet

groundings, and somewhat reduce the

substantial economic burden to the

airlines.

The FAA does not concur with the

commenter’s statement that the

requirements of the final rule should be

recast into phases. As discussed above

under the heading ‘‘Unsafe Condition,’’

potential ignition sources exist in many

areas of the affected airplanes. It is

difficult to identify high risk areas and

areas of little or no risk. Therefore, the

FAA finds that MPET insulation

blankets in all areas of the affected

airplanes must be replaced. With the

change in the compliance time from 4

to 5 years in this AD, excessive fleet

grounding should not take place.

Adequate maintenance facilities are

available to complete this action within

the required time period.

Compliance Time for Proposed

Replacement of MPET Insulation

Blankets

Several commenters request that the

compliance time for accomplishing the

proposed replacement of the MPET

insulation blankets be extended from

the proposed 4 years to a range of 5

years to 8 years. The commenters state

that such an extension will allow the

replacement to be accomplished during

a regularly scheduled ‘‘D’’ check or

heavy maintenance visit, thereby

eliminating any additional expenses

that would be associated with special

scheduling. The commenters express a

concern about the availability of

facilities and trained personnel, either

domestically or offshore, to accomplish

tasks of this magnitude.

One commenter states that

maintenance planning can only be done

effectively once all details of the work

to be accomplished and all downtimes

needed to perform the work are known

in detail. Therefore, the compliance

time should only start once all these

details have been clarified.

One commenter states that the

proposed AD’s do not provide sufficient

time for accomplishment of the

prototyping effort. Wholesale removal or

relocation of wiring not designed for

removal in areas where access is

difficult can lead to incidental damage

even with the best maintenance

practices. Given the problems of access,

multiple blanket sections will now be

required in many fuselage areas to

replace a single original blanket. This

will lead to new designs, templates, and

part numbers. The commenter

concludes that this cannot happen in an

orderly fashion without completing a

prototyping effort on at least one

airplane.

The FAA concurs that an extension to

the compliance time is warranted. The

FAA’s intent was that the replacement

be conducted during a regularly

scheduled maintenance visit for the

majority of the affected fleet, when the

airplanes would be located at a base

where special equipment and trained

personnel would be readily available, if

necessary. Based on the information

supplied by the commenters, the FAA

now recognizes that 5 years corresponds

more closely to an interval

representative of most of the affected

operators’ normal maintenance

schedules. The FAA finds that a 4-year

compliance time would have a

significant impact on scheduling and

cost and might result in hurried

accomplishment of the required

replacement, which could result in

potential damage to associated wiring.

This decision is supported by

experience from the prototype

installations, which demonstrated that

the required replacement procedures are

complex in some areas, and that

adequate time and facilities are

necessary to ensure that they are

completed safely and correctly.

Paragraphs (a) and (c) of the final rule

have been revised to reflect a

compliance time of 5 years. The FAA

does not consider that this extension

will adversely affect safety.

One commenter supports the

proposed 4-year compliance time for

accomplishing the proposed

replacement of the MPET insulation

blankets. The commenter states that,

while some operators feel it is not a

practical time period, the proposed

compliance time is reasonable and

practical to retrofit all of the affected

airplanes, utilizing airline and third

party maintenance facilities. The

commenter also states that it and other

materials manufacturers are fully

prepared and have the capacity to

support this effort. Another commenter

states that the proposed 4-year

compliance time is a very generous

allotment of time and would not want

to see the proposed AD’s delayed any

further.

The commenters did not provide any

data to support their position. For the

reasons described previously, the FAA

finds that a 5-year compliance time is

reasonable and practical to retrofit all of

the affected airplanes rather than the 4-

year compliance time proposed by the

original NPRM and supplemental

NPRM.

Two commenters request that the

compliance time for accomplishing the

proposed replacement be shortened.

One commenter states that the proposed

compliance time of 4 years is too

lengthy given the fire hazard introduced

by MPET insulation blankets. The

second commenter states that quicker

action is necessary if the conditions of

the wiring on affected airplanes are

anything like what was discovered in

the 737’s emergency grounding issue of

May 98, wires found damaged on the

Space Shuttle Columbia, or numerous

instances of wire insulation failure

coming out of the Aging Transport

Systems Rulemaking Advisory

Committee (ATSRAC)/ASTF

inspections (15 service bulletins

upgraded to alert status on Model MD–

11 series airplanes alone) or alert service

bulletins on the 727’s.

The FAA does not concur with the

commenter’s request to shorten the

compliance time. As discussed

previously, the FAA considered the

safety implications, parts availability,

and normal maintenance schedules for

timely accomplishment of replacement

of the MPET insulation blankets. In

consideration of all of these factors, the

FAA determined that the compliance

time, as revised, represents an

appropriate interval in which

Federal Register / Vol. 65, No. 103 / Friday, May 26, 2000 / Rules and Regulations 34325

replacement of the MPET insulation

blankets can be accomplished in a

timely manner within the fleet and still

maintain an adequate level of safety.

The FAA encourages operators to

accomplish this modification as soon as

possible. The commenter points out

several incidents associated with

airplane wiring. The FAA is addressing

these issues as they are identified. The

commenter is correct that these wiring

incidents are the focus of ATSRAC and

ASTF activity. However, these wiring

issues are not the subject of this AD.

One commenter requests that the FAA

consider a 4-year compliance time to

accomplish the proposed replacement

only in areas that are readily accessible

(i.e., areas where extraordinary means

are not required to gain access). The

MPET insulation blankets for certain

defined areas of the cockpit and

electronics bay(s) should not be

replaced or should be replaced when

those areas are made accessible. The

commenter states that replacement of 98

percent of the insulation on the affected

airplanes will provide an equivalent

level of safety to those airplanes not

affected by the proposed AD’s.

Considerable time will have to be added

to the proposed compliance time to

accommodate a complete replacement

without forcing some airplanes to be

grounded due to lack of maintenance

capacity.

The FAA does not concur with the

commenter’s request to require a

compliance time of 4 years only for

replacement areas that are readily

accessible. Although the prototype

installations have shown that

accomplishment of the required

replacement in the cockpit and

electronic compartment is physically

challenging, potential ignition sources

and the identified unsafe condition exist

in areas that are not readily accessible.

Therefore, the FAA finds that MPET

insulation blankets in all areas of the

affected airplanes must be replaced.

However, as discussed previously, the

FAA has extended the compliance time

for the required replacement from 4

years to 5 years. While not intended to

address the issue of inaccessible areas,

the extension of the compliance time by

one year should help alleviate the

concern for grounding of airplanes due

to lack of maintenance capacity.

Two commenters request that the

FAA ensure that sufficient insulation

material of appropriate quality is

available. Supply shortages could create

conditions in which the work needs to

be performed under time pressure. One

commenter notes that there is only one

blanket covering material that is

currently approved, and only one

qualified test apparatus available for

operators to perform American Society

for Testing and Materials (ASTM) E648

tests on other products. The commenter

also notes that the airplane

manufacturer has stated that it has only

one qualified supplier for manufactured

blankets. The commenter is uncertain if

the blanket manufacturer can meet

replacement demands within the

proposed 4-year compliance time.

Furthermore, the commenter states that

there are no dimensioned drawings

available to 14 CFR part 121 operators

who might plan to fabricate their own

blankets. Templates must be plotted and

obtained from the airplane

manufacturer, which is a time

consuming process.

Various insulation blanket material

suppliers state that there is no cause for

concern over the availability of the

materials specified in the proposed

AD’s. Metallized TedlarTM (i.e.,

polyvinylfluoride), polyimide film,

TedlarTM and polyimide tapes, and

fiberglass are abundant and are readily

accessible to support all retrofit

requirements.

The FAA has assessed the availability

of materials required by this AD and has

determined that required materials and

manufacturing sources should be

available for modification of the U.S.

fleet within the 5-year compliance time.

The FAA encourages operators to

review their airplanes to assess their

individual needs for materials and plan

accordingly. The FAA anticipates that

operators will accomplish the

requirements of this AD at the earliest

practicable maintenance opportunity to

lessen the burden toward the end of the

compliance time. In addition, the

airplane manufacturer is preparing

installation kits that can be utilized to

accomplish the required replacement.

Also, operators and modifiers have

developed and are continuing to

develop their own data (templates and

drawings) to accomplish this required

replacement. While this may be a time

consuming process for some, it can be

accomplished.

Inadequate Procedures and Information

in Referenced Service Bulletins

Several commenters state that the

replacement procedures and

information specified in the referenced

service bulletins (i.e., McDonnell

Douglas Service Bulletins MD–90–25–

015, Revision 01, dated November 5,

1997; MD80–25–355, Revision 01, dated

November 5, 1997; DC10–25–368, dated

October 31, 1997; and MD11–25–200,

Revision 01, dated March 20, 1998) are

inadequate for reasons discussed below.

Several commenters state that the

Accomplishment Instructions of the

referenced service bulletins address the

fabrication of insulation blankets but

provide no instructions for installation.

Detailed instructions for installation are

essential to avoid risks during

installation, particularly in crucial areas

where wiring or other systems are

densely concentrated. Damage to

installed systems can result in latent

failures of critical flight systems and

generation of electrical ignition sources.

The unprecedented scope of the work

involved in moving and replacing wires

and systems, and the fact that nothing

similar has ever been attempted,

introduce a new and unquantified

amount of risk.

One commenter states that Boeing has

acknowledged that instructions to

remove and reinstall some equipment

racks and related structures, which are

necessary to accomplish the proposed

replacement, do not exist in current

maintenance documents and will need

to be developed. Specific aspects of the

proposed replacement are beyond the

scope of any currently authorized

maintenance procedures. The members

of the Boeing Recovery and

Modification (RAM) Team are the only

personnel trained and authorized to

disassemble and reassemble certain

critical areas. Several commenters state

that Boeing is planning to issue revised

service bulletins around June 2000. One

commenter states that Boeing should

issue detailed service bulletins to cover

the scope of the NPRM’s and all related

test criteria and requirements associated

with insulation blanket replacement and

removal/installation of associated

equipment/components. One

commenter states that the service

bulletins should be revised to include

the above information.

The FAA acknowledges that the

instructions appear to be generic,

without reference to specific locations

in the airplane. However, it is still

possible to complete the replacement

required by this AD by developing the

necessary installation data in

conjunction with existing maintenance

procedures. Since the issuance of the

NPRM’s, the manufacturer, in

conjunction with operators, has

completed prototype installations.

Based on the results of the prototype,

the manufacturer is developing

revisions to the referenced service

bulletins that will contain additional

installation information and

instructions. These revised service

bulletins are scheduled for completion

in June 2000. Any new or revised

service bulletins will contain

procedures to maintain/test the integrity

34326 Federal Register / Vol. 65, No. 103 / Friday, May 26, 2000 / Rules and Regulations

of the wiring after accomplishment of

the replacement of any MPET insulation

blanket. The FAA is planning to review

and approve the revised service

bulletins under the AMOC provision of

paragraph (e) of the final rule.

In addition, the FAA is aware that

certain operators and modifiers are

developing their own installation data.

The FAA may approve requests for an

AMOC under the provisions of

paragraph (e) of this AD if sufficient

data are submitted to substantiate that

such a design change would provide an

acceptable level of safety.

The FAA does not concur with the

commenter that the members of the

Boeing RAM team are the only

personnel that can address certain areas

of the airplane. The FAA finds that

many operators have the expertise to

accomplish the required replacement. In

addition, Boeing intends to include the

necessary instructions in the revised

service bulletins.

Several commenters state that the

referenced service bulletins not only

refer to materials tested in accordance

with Standard Test Method ASTM E648

and approved by the FAA as a method

of compliance with the requirements of

the proposed AD, but also refer to

materials that do not meet the new

requirements. Moreover, other materials

acceptable for compliance with the

requirements of the proposed AD are

not listed in the referenced service

bulletins.

The FAA concurs that the referenced

service bulletins refer to materials that

do not meet the requirements of this

AD. When the referenced service

bulletins specified in the NPRM’s were

issued in 1997, the insulation blanket

film material listed in those service

bulletins were considered acceptable for

installation. Since the issuance of those

service bulletins, however, only one of

the two metallized TedlarTM covers

specified in the referenced service

bulletins has been demonstrated to be

acceptable for compliance with the

replacement requirements of paragraph

(c) of this AD (as indicated in NOTE 4

of the AD) based on flammability testing

using the criteria specified in the final

rule. The revised service bulletins will

only list material that has been

approved by the FAA. Under the

provisions of paragraph (c) of this AD,

the FAA may approve other film

material that is shown to meet the

flammability test method specified in

the final rule. Also, under the

provisions of paragraph (e) of this AD,

the FAA may approve requests for

approval of an AMOC for insulation

blankets other than those specified in

the service bulletins referenced in the

final rule that are shown to meet the

flammability test method specified in

the final rule and all other airworthiness

regulations.

Several commenters state that, due to

age, identification stamps on the MPET

insulation blankets may be unreadable.

The referenced service bulletins are

missing instructions for determining

whether such blankets are constructed

of MPET.

Although the referenced service

bulletins are missing instructions for

determining whether insulation

blankets are constructed of MPET, the

FAA finds that such a determination

can be made without such instructions.

MPET insulation blankets are extremely

shiny when compared to all other

insulation blanket cover material, and

can be readily recognized by trained

maintenance personnel. It is also

possible to use known MPET material as

a comparison sample to assist in the

identification should the markings not

be readable. Paragraph (a) of the final

rule has been revised to clarify the

method of identifying MPET. MPET

insulation blankets can be identified by

the following markings: (1) DMS 2072,

Type 2, Class 1, Grade A; (2) DMS 2072,

Type 2, Class 1, or (3) DMS 1996, Type

1. The FAA has revised NOTE 2 of the

final rule to clarify these markings.

Several commenters state that the

referenced service bulletins specify the

least effective method for the fabrication

of new insulation blankets. Few

operators are equipped or have the

capability or capacity to manufacture

their own blankets. Four sources of

insulation blankets were evaluated in

technical meetings with the

manufacturer. Of these four sources,

operators viewed blankets provided in

kits by the manufacturer as the most

efficient and practical. Such kits would

facilitate the earliest completion date of

a replacement program, would preserve

the thermoacoustic characteristics of

insulation systems and certificated

configuration of affected airplanes, and

can be supported according to the

manufacturer. In addition, no

dimensional blanket drawings and

templates for making the blankets are

available.

Although the method for fabrication

of new insulation blankets specified in

the referenced service bulletins may not

be the most efficient method for the

commenters, the FAA finds that it is

possible to develop the necessary data

to manufacture blankets in accordance

with the instructions of the referenced

service bulletins. The FAA is aware that

Boeing is developing replacement kits.

The information necessary to purchase

these kits will be included in the

revised service bulletins (as discussed

previously). However, the revised

service bulletins are not scheduled to be

completed until June 2000. The FAA

has decided not to delay this action in

anticipation of the service bulletins,

since the release date is not absolute

and this action is necessary to address

an identified unsafe condition.

Therefore, the FAA may approve

requests for an AMOC under the

provisions of paragraph (e) of this AD

once the revised bulletins are issued.

In addition, the FAA acknowledges

that templates may not be available for

operators to make new insulation

blankets. However, the referenced

service bulletins do describe procedures

for removing the subject insulation

blankets and using those blankets as

templates for making new insulation

blankets. While some operators may not

be equipped or may decide not to

manufacture the replacement blankets,

there are adequate resources available in

the industry to accomplish the

manufacturing.

Several commenters state that the

referenced service bulletins provide no

labor estimates. One commenter states

that it is not aware of any large transport

category airplane that has been removed

from service, has had its insulation

replaced, and has been returned to

service. This lack of experience and

labor estimates from the manufacturer

would impair the planning required of

operators and their ability to provide

accurate comments to the proposed

AD’s.

The FAA does not concur. The FAA

acknowledges that the referenced

service bulletins do not provide labor

estimates. However, as indicated under

the heading ‘‘Regulatory Evaluation

Summary’’ in the preamble of the

NPRM’s and supplemental NPRM’s, a

Preliminary Cost Analysis and Initial

Regulatory Flexibility Analysis to

determine the regulatory impacts of the

proposed AD’s were included in the

Rules Docket No.’s 99–NM–161–AD and

99–NM–162–AD. A summary of those

analyses was contained under that same

heading in the preamble of the NPRM’s

and supplemental NPRM’s. In addition,

the manufacturer, operators, and

modifiers have developed estimates

based on the prototype installations

completed to date. (The FAA discusses

the comments to the cost estimate of the

proposed AD’s in more detail, below,

under the heading ‘‘Regulatory

Evaluation Summary.’’)

In response to the original NPRM’s,

several commenters state that the

manufacturer has indicated that the

airplane effectivity in the referenced

service bulletins is currently being reVerDate 11<MAY>2000 20:26 May 25, 2000 Jkt 190000 PO 00000 Frm 00006 Fmt 4701 Sfmt 4700 E:\FR\FM\26MYR2.SGM pfrm03 PsN: 26MYR2
Federal Register / Vol. 65, No. 103 / Friday, May 26, 2000 / Rules and Regulations 34327

evaluated and may be revised

substantially. This lack of accurate

airplane effectivity also would impair

the planning required of operators and

their ability to provide accurate

comments.

The FAA concurs that the effectivity

listed in the service bulletins is not

correct. As indicated under the heading

‘‘Differences Between the Proposed AD

and Service Bulletins’’ in the preamble

of the NPRM’s, the FAA realizes that the

effectivity listing of the referenced

service bulletins not only includes

airplanes manufactured with MPET

insulation blankets, but airplanes

equipped with other materials that are

much more difficult to ignite than

MPET. The FAA has determined that

only airplanes manufactured with

MPET insulation blankets are subject to

the identified unsafe condition.

Therefore, paragraph (a) of the AD’s

requires that a determination be made of

whether, and at what locations, MPET

insulation blankets are installed. In

addition, the applicability specified in

the final rules, based on the

supplemental NPRM’s, includes fewer

airplanes than specified in the service

bulletins. In addition, the applicability

statement of the final rule, Rules Docket

No. 99-NM–162-AD, has been revised to

clarify the airplanes that are subject to

the identified unsafe condition, which

is discussed below, under the heading

‘‘Revise Applicability of Proposed AD.’’

Several commenters state that some

accessibility issues have not been

addressed. One commenter requests that

the removal/replacement requirements

be re-evaluated to exclude replacement

insulation blankets in those

‘‘inaccessible places’’ of the airplanes.

Three to four percent of the MPET

insulation blankets are buried beneath

structure and wiring in areas like the

electrical and equipment (EE) bay and

the flight deck and will require as much

as 70 percent of the total man hours to

replace.

The FAA does not concur that

replacement of MPET insulation

blankets should not be required in

‘‘inaccessible’’ areas. The areas

identified by the commenters (i.e., the

EE bay and flight deck) are areas where

potential ignition sources (i.e., electrical

arcing) are likely to exist and are,

therefore, susceptible to the identified

unsafe condition. During the prototype

exercises and subsequent inspections of

the EE bay and flight deck, the FAA

learned that most Model DC–9–80 and

MD–90–30 series airplanes do not have

MPET insulation blankets in these areas.

It is, however, the operator’s

responsibility, as required by paragraph

(a) of this AD, to determine whether,

and at what locations, MPET insulation

blankets are installed in each airplane.

Therefore, contrary to the commenters’

assertion, the total labor costs associated

with replacement of the MPET

insulation blankets in the EE bay and

flight deck will not be the most

significant portion of the total cost of

the AD.

One commenter requests that the FAA

revise the proposed AD to incorporate

specific references to industry guidance

material on wire inspection and

disturbance. As a minimum, such

references should include Advisory

Circular 25–16, ‘‘Electrical Fault and

Fire Protection and Prevention.’’

The FAA does not concur. Operators

and modifiers should be aware of the

existing guidance and the revised

service bulletin instructions (discussed

above), which, based on the prototyping

that has been accomplished, will specify

wiring inspection information that may

be needed.

One commenter requests that the FAA

develop and require post-modification

wiring inspections to verify the integrity

of the wiring insulation. The FAA

concurs that any damage done to wiring

or other components in the course of the

required replacement needs to be

corrected. In fact, if maintenance

personnel are aware of damage, whether

or not caused by replacement of the

MPET insulation blankets, they are

obligated to document it and initiate

appropriate corrective action. Operators

are required by 14 CFR parts 91, 121,

and 135 to maintain their airplanes in

an airworthy condition after any

alteration or repairs are made to the

airplane. Also, based on the prototyping

that has been accomplished, the revised

service bulletins will provide any

specific wire integrity inspection that

may be needed. Therefore, no change to

the final rule is necessary.

Coordination With Wiring AD’s

Several commenters state that they

understand that other NPRM’s are in the

development phases, which would

require inspection of airplane wiring,

and would deal with the same issues

that have brought about the subject

proposed AD’s. Some of these

commenters state that these NPRM’s

should not be developed, mandated,

and undertaken separately, but rather

should be part of a carefully thought out

and coordinated process and program. A

properly developed plan must consider

that each time such disruption of

airplane wires/systems takes place,

there is an increasing opportunity for

collateral damage to those wire/systems

with unknown future safety

implications. Such a plan also should

recognize that the insulation proposed

to be changed is not really the source of

any fire problem and that proper

rectification of the issues being

considered might better lie in a carefully

thought out and researched wiring AD.

One commenter states that it would be

efficient to combine the requirements of

the proposed AD’s with the wiring

requirements that will be proposed

soon. One commenter states that Boeing

is developing several service bulletins

dedicated to the inspection and

maintenance of airplane wiring.

However, these service bulletins will

not be available in time to coincide with

the insulation blanket replacement

should the current NPRM’s, with their

proposed timing, become law.

The FAA does not concur that AD’s

addressing specific unsafe wiring

conditions should necessarily provide

for compliance times that are concurrent

with this AD. In some cases, the

corrective actions for those unsafe

conditions are simple maintenance

actions that can be accomplished

quickly. It would be inappropriate to

allow those unsafe conditions to

continue during the extended

compliance time allowed by this AD.

The FAA does concur that any AD’s

addressing general wiring inspections

for unsafe conditions would be best

accomplished in conjunction with the

replacement of MPET insulation

blankets in affected areas. Such

coordinated actions would certainly be

most efficient for operators. The FAA

does not concur with the commenters’

request to combine the requirements of

this AD with any proposed actions to

address general wiring issues. Such

action may delay correction of the

unsafe condition of this AD by

extending the compliance time further.

The FAA will take into consideration

the compliance time of this AD in any

future action for general wiring

inspection to minimize the duplication

of aircraft downtime associated with

accomplishing the actions of this AD.

Revise Applicability of Proposed AD

One commenter notes that paragraph

(a) of the proposed AD states ‘‘* * *

determine whether, and at what

locations, insulation blankets

constructed of MPET are installed. This

determination shall be made in a

manner approved by the FAA.’’ The

commenter states that this wording is

very unclear to operators and that the

FAA should coordinate with Boeing to

determine more precisely what the

applicable airplanes are.

Based on the commenter’s statement

that ‘‘the FAA should coordinate with

Boeing to determine more precisely

34328 Federal Register / Vol. 65, No. 103 / Friday, May 26, 2000 / Rules and Regulations

what the applicable airplanes are,’’ the

FAA finds that clarification is

necessary. After inspecting in-service

airplanes, the FAA has determined that

all affected airplanes may not have

MPET insulation blankets throughout

the fuselage. Some airplanes may have

very little MPET insulation blankets

installed and others may have 100

percent installed. The FAA also has

determined that, based on the

manufacturer’s records alone, it is not

possible to determine precisely the

configuration of each individual

airplane. Therefore, paragraph (a) of the

final rule requires that operators

determine whether, and at what

locations, insulation blankets

constructed of MPET are installed. If

MPET insulation blankets are not

installed, no further action is required

by this AD.

The manufacturer states that it is

continuing to verify the actual extent of

MPET-covered insulation on airplanes

delivered from the factory. In response

to the original NPRM’s, the

manufacturer states that additional

Model DC–9–87 (MD–87), DC–10, and

MD–11 series airplanes, and KC–10A

(military) airplanes need to be included

in the applicability of the NPRM’s, and

at least some Model DC–9 series

airplanes should be excluded. When

that effort is complete, the manufacturer

states that it will issue new service

bulletin information. One commenter

states that the applicability statement of

NPRM, Rules Docket No. 99–NM–162–

AD, is incorrect. The commenter states

that the manufacturer has indicated that

MPET insulation blankets were used on

Model DC–10 series airplanes, fuselage

numbers 359 through 381 inclusive, and

432 through 436 inclusive, and Model

MD–11 series airplanes, fuselage

numbers 447 through 602 inclusive. In

addition, MPET insulation blankets

were used on ducting installed in Model

MD–11 series airplanes, fuselage

numbers 603 through 632 inclusive.

The FAA acknowledges that the

applicability statement of the original

NPRM’s was incorrect. Following the

issuance of the NPRM’s, the FAA

identified additional airplanes that were

subject to the identified unsafe

condition and issued supplemental

NPRM’s to reopen the comment period

to provide additional opportunity for

public comment. The applicability

statement of the supplemental NPRM’s

included the fuselage numbers of the

airplanes the commenter referred to

above.

One commenter states that the

applicability statement of supplemental

NPRM, Rules Docket No. 99–NM–162–

AD, is incomplete. The commenter

notes that it operates four Model DC–

10–15 series airplanes, three of which

fall within fuselage numbers 359

through 632 inclusive (i.e., fuselage

numbers 362, 365, and 374), which were

manufactured between June 1981 and

January 1982. The commenter requests

that the applicability statement of the

supplemental NPRM be revised to

include Model DC–10–15 series

airplanes. The FAA concurs. The

applicability statement of the subject

supplemental NPRM correctly

references the specific manufacturer’s

fuselage numbers of all affected

airplanes, including those fuselage

numbers for Model DC–10–15 series

airplanes. Therefore, the FAA finds that

it is necessary to revise the applicability

statement of the subject final rule to

include all affected series of Model DC–

10 airplanes, specifically Model DC–10–

10F, DC–10–15, and DC–10–40 series

airplanes.

One commenter requests that the

applicability of NPRM, Rules Docket

No. 99–NM–161–AD, be revised to

‘‘[m]anufacturer’s fuselage number 1011

through 2241 inclusive; certified in

common carriage operations.’’ The

commenter states that private operators

were not considered when studying the

effects of the proposed AD’s. Private

operators who operate under 14 CFR

91.501 need to be separately considered

when they are faced with rules that are

directed at air carriers. Transport

category ‘‘Private Carriage’’ operators,

who operate under 14 CFR 91.501, are

part of the general aviation population

and do not offer service to the public or

a segment of the public. General

aviation operators’ airplanes are not

held (and are not expected to be held)

accountable to the same regulation

standards as ‘‘Common Carriage’’

operators. The commenter also states

that significant differences in airplane

utilization, interior, and operation make

the likelihood of in-flight fire threat due

to MPET insulation blankets on ‘‘Private

Carriage’’ airplanes extremely remote.

Therefore, the exclusion of ‘‘Private

Carriage’’ airplanes from the

applicability of this NPRM would not

jeopardize public interest.

The FAA does not concur with the

commenter’s request to revise the

applicability of the subject rule as

stated. The identified unsafe condition

and potential consequences addressed

by this AD are not any different for

airplanes utilized in private operation

versus ones operated in common

carriage.

One commenter states that the

proposed AD’s do not address affected

airplanes outside the noted applicability

that may have been retrofitted with

MPET insulation blankets during

service. This implies that the FAA’s

investigation has determined that small

amounts of MPET on those airplanes do

not pose an unsafe condition.

Regarding post-delivery installation of

MPET, the FAA does consider that such

insulation is unsafe. Most operators do

not retain records identifying on what

airplanes such insulation has been

installed. Therefore, to address this

unsafe condition, an AD would have to

require that all operators inspect all

airplanes of any type to identify the

relatively small amount of such

insulation that may have been installed

during post-production maintenance.

The FAA does not consider that such a

requirement would be practical or cost

effective. However, as with any other

unsafe condition, when an operator

becomes aware that MPET insulation

blankets have been installed, the

material should be removed to maintain

the airplane in an airworthy condition.

Flammability Test Method Not

Adequately Developed/Defined

Several commenters state that the

proposed test method seems

insufficiently developed to be

considered the new standard

flammability test. The commenters

addressed several issues, including:

• The validity of the test method;

• Qualification of the test method;

• Details of the test procedures; and

• Materials and approval process.

Validity of Test Method

One commenter notes that it has built

a test unit and conducted tests on it.

The commenter has verified the results

of the FAA Technical Center tests, but

believes there are serious limitations on

this test’s utility for predicting how

insulation coverings will burn when in

place on an airplane. In addition, the

commenter states that the mechanism

by which films can pass the Radiant

Panel Test is for the material to shrink

away from the heat source. Other

materials, such as polyimide film, pass

the Radiant Panel Test by not igniting

and shrinking away from the heat

source. Two other commenters state that

the best of TedlarTM and MylarTM (i.e.,

3 polyethyleneteraphthalate) films

shrink away in the presence of flame

and are no help at all in containing fire.

The TedlarTM material that passes the

test shrinks away from the heat source

before the ignition source can be

applied to the surface of the test

material. Thus, there is no material to

ignite. The commenter states that the

Radiant Panel Test may not replicate the

condition on an airplane where blankets

Federal Register / Vol. 65, No. 103 / Friday, May 26, 2000 / Rules and Regulations 34329

are restrained and multiple layers are

often part of the blanket construction.

The commenter further states that it is

possible for polyethyleneteraphthalate

(PET), MPET, or other plastics that are

more combustible than TedlarTM to pass

ASTM E648, if treated to have desirable

heat shrink characteristics. The only

other requirement for insulation

coverings is the 12-sec vertical burn,

which is recognized as inadequate

because MPET materials can pass it. The

commenter notes that the proposed

standard may leave the door open in the

future for combustible materials to be

installed on airplanes.

The FAA does not concur with the

commenter’s statement that films can

pass the Radiant Panel Test by shrinking

away from the heat source and are no

help in containing a fire. The purpose

of the test is to establish the flame

spread characteristics of insulation

blanket materials under realistic

conditions. The results of this test have

been correlated with full-scale testing,

conducted by the FAA Technical

Center, in which insulation was

installed in fuselage sections in a

representative fashion. Certain materials

that shrink when exposed to heat have

been shown to prevent propagation of a

fire. In addition, for these same reasons,

the FAA does not concur with the

commenter that the FAA Technical

Center tests have serious limitations.

The FAA finds that the insulation

material tested in accordance with the

method specified in the AD will have

much better flame spread characteristics

than MPET, which was shown to

comply with the current Bunsen Burner

Test specified in the regulations, and

subsequently, determined to have

unsafe flame spread characteristics

when ignited from a small ignition

source.

One commenter states that the best

situation is to have insulation covering

film that does not burn in the Radiant

Panel Test. The commenter contends

that the test should screen out material

that does not perform as well as

polyimide film.

The FAA does not concur that the test

method must screen out materials that

do not perform as well as polyimide

films. As discussed previously,

materials, including polyimide films,

that pass the Radiant Panel Test perform

much better in full-scale testing than

MPET insulation blankets that are the

subject of this AD.

Qualification of the Test Method

One commenter expresses concern

that the FAA has not yet published

updated flammability standards that

will allow for the development and

testing of materials other than those

cited in previous McDonnell Douglas

service bulletins, which specify the

replacement of MPET with two types of

metallized TedlarTM. The commenter

notes that the FAA has approved only

one type of specified metallized

TedlarTM after it successfully passed an

ASTM flame spread test. The

commenter emphasizes that it is urgent

that the FAA provide its own applicable

test standard to facilitate the rapid

replacement of MPET with other

materials that will have superior fire

resistant characteristics.

One commenter requests that the FAA

revise the proposed AD’s to ‘‘more

clearly require the FAA Radiant Panel

Test, which was derived from ASTM

E648,’’ and to define the test before

approving specific films. The

commenter states that ASTM E648 is

much different than the Radiant Panel

Test developed by the FAA Technical

Center. The Radiant Panel Test uses the

same enclosure, a radiant panel, and the

same basic concept as the ASTM E648

test. However, the Radiant Panel Test

has had several modifications including

a different heat flux, different ignition

source, and a modified sample holder.

The commenter notes that results of the

Radiant Panel Test vary widely when

test specifications are changed.

Therefore, the specification of any film

as passing the test prior to the

completion of the test method is not

warranted. It is possible for films that

currently fail the existing test to pass

when the test procedures or chamber is

fully defined. Conversely, films that

currently pass the test can fail.

One commenter states that industry

experts should discuss the success

criteria of ASTM E648 further. This

commenter notes that these changes to

the standard and success criteria have

not been subject to round robin testing

and outside peer review, so various

aspects of their merit are questionable.

One commenter suggests that round

robin testing with clearly identifiable/

achievable pass/fail criteria be

performed by the industry to validate

the repeatability of the test procedures

prior to release of the proposed AD’s.

Validated criteria would produce an

equivalent level of safety to material

currently in production and in use in

the fleet, which is deemed acceptable.

The FAA concurs with the

commenters concerning the reference to

ASTM E648 in the NPRM’s and finds

that clarification is necessary. The FAA

has been developing for some time new

flammability standards for insulation

material. Research has been conducted

on the various types of insulation

material to determine their effectiveness

on both flame spread and fuselage

burnthrough. As a result, the FAA has

developed a new flame spread test

method. The flame spread test method

specified in this AD is a modified

version of the ASTM E648 flammability

standard and test apparatus.

Modifications to ASTM E648 test

apparatus have been made to more

closely reflect the fire conditions in an

airplane environment. The FAA has

prepared a document to reflect the flame

spread test method to be used for testing

of replacement insulation blankets for

this AD. It is identified as ‘‘Test Method

to Determine the Flame Spread

Characteristics of Thermal/Acoustic

Insulation Material for Replacement of

MPET.’’ For the purposes of correcting

the identified unsafe condition of this

AD, the FAA finds that this flame

spread test method is sufficiently

developed.

The FAA also has developed a

procedure for utilizing the FAA

Technical Center flame spread test

apparatus to qualify materials for this

AD. The procedure for utilizing the test

apparatus of the FAA Technical Center

is identified as ‘‘Ground Rules for Use

of Technical Center Facility for

Testing.’’

The flame spread test method and

procedure for using the FAA Technical

Center test apparatus are both included

in Appendix 1 of this AD.

As paragraph (c) of the NPRM’s is

currently worded, some commenters

may misinterpret that the replacement

insulation blankets must be constructed

of materials tested in accordance with

the original ASTM E648 flammability

standard, rather than tested in

accordance with a new flame spread test

using an apparatus derived from ASTM

E648 in accordance with a method

approved by the FAA. Paragraph (c) of

the final rules has been revised to clarify

the flame spread test method for

replacement insulation blankets. The

Los Angeles Aircraft Certification Office

(ACO) will work closely with other FAA

ACO’s and the FAA Technical Center to

assist operators/modifiers in qualifying

new materials for compliance with the

requirements of this AD.

The FAA concurs that the method

specified is not yet a ‘‘standard.’’

However, the method is sufficiently

developed for this AD and, before

adoption as a standard, will undergo the

kind of industry qualification proposed

by one commenter. The FAA partially

concurs with the commenter’s statement

that round robin testing is necessary and

that the success criteria of the flame

spread test method should be discussed

further. Prior to incorporation of a new

flame spread test method into the

34330 Federal Register / Vol. 65, No. 103 / Friday, May 26, 2000 / Rules and Regulations

Airworthiness Standards for transport

category airplanes (14 CFR part 25), the

test method will be subject to round

robin testing. In fact, this process is

currently underway within the

International Aircraft Materials Fire Test

Working Group.

With respect to changes in the flame

spread test method that may cause

certain materials to go from acceptable

to unacceptable, or vice versa, the FAA

does not agree that this is an issue.

Refinements to the test method will be

made to improve the repeatability of the

test, not to change the test results.

Materials that are marginal will perform

marginally regardless of the details of

the method.

One commenter states that it

understands that the FAA has plans to

replace the standard gas-fired radiant

panel with an electric panel, and that

the flame ignition source is a single

cone non-standard burner as opposed to

the T-type burner method specified in

ASTM E648. The commenter contends

that differences between the FAA

method and ASTM E648 are confusing

to both testing labs wishing to provide

services to FAA-regulated clients as

well as suppliers of insulation who are

unclear as to what the specification will

be for the products they produce for the

aerospace industry. The commenter

states that ‘‘specification of a nonstandard test apparatus and conditions

by the FAA end up creating a whole

other set of devices which must be

fabricated and maintained separately

from their standard ‘parent devices’

removing the economic benefits which

use of consensus developed public

sector standards provide.’’

The FAA does not concur for the

reasons noted previously. In addition,

since the apparatus specified is not used

for any other aviation application, there

is very little potential for confusion. The

number of facilities currently equipped

to conduct these tests is extremely

small, which further diminishes any

problems associated with differences in

the test method.

One commenter states that, because of

such a tremendously costly retrofit

program, all further developments with

regard to new testing methods must

clearly avoid duplication or

contradiction of actions as described in

the proposed AD’s.

The FAA has revised paragraph (c) of

the final rule to clarify the flame spread

test method to be used to qualify

replacement insulation blankets. As

previously discussed, this test method is

adequately refined to qualify these

materials for this AD.

Details of the Test Procedures

One commenter states that results of

tests have shown that the thickness of

the insulation has no impact on the

performance of the film under test.

Therefore, the commenter suggests that

all samples be tested with two-inch

thick insulation.

One commenter requests that the FAA

develop specifications for

environmental conditioning of samples

since the absence of such requirements

will significantly alter test results, in

particular for ignition and flame spread

sensitive materials such as faced

insulation.

The commenter states that the

proposed pass/fail criteria, including

the minimum 2-inch burn length and 0

flame spread, are not easily measured or

agreed upon. Several commenters state

that clearer pass/fail criteria are needed.

One commenter states that subjective

assessment of test results in small scale

fire testing is a constant, ongoing

problem that should be avoided.

One commenter claims that the

‘‘pilot’’ burner arrangement called out in

the FAA specification does not result in

reproducible test results. Likewise, the

‘‘pre-heat’’ time between specimens and

the time between sample insertion and

flame application have not been

defined. The commenter prefers a

standard design and operation

conditions and is unclear why the

standard design has been modified.

The FAA does not agree that the

current test method lacks

reproducibility. Tests conducted at the

FAA Technical Center and at other

facilities indicate that the test is

reproducible and repeatable. The FAA

concurs with the commenter that a

defined test protocol should be used

when testing replacement material. The

flame spread test method specified in

the final rule does include the pass/fail

criteria, environmental conditioning,

and test specimen thickness. Issues such

as the pilot burner arrangement will be

the subject of further refinement before

the test method is adopted as a

regulatory standard, but are adequately

defined for this AD.

One commenter requests that the test

procedures include contaminated

insulation blankets to simulate real

world conditions. The commenter states

that testing of pristine material may not

provide sufficient assurance when

within a few years the thermal blankets

will be contaminated with solvents and

other material. The FAA does not

concur. While ‘‘contamination’’ might

result in either detrimental or improved

flammability performance,

incorporation of generic

‘‘contamination’’ into a test requirement

is not practical. Contamination is

usually a localized phenomenon, and

not spread uniformly throughout the

airplane. Replacing the existing

materials with materials that will not

propagate a fire will confine a fire to the

area of contamination and should

prevent the fire from becoming a hazard.

As with any material installed on an

airplane, it is the operator’s

responsibility to ensure that the airplane

remains in an airworthy condition.

The commenter further requests that

the test procedures include ignition ‘‘by

these so-called, otherwise harmless

electrical arcs.’’’ The commenter states

that the likelihood of thermal blankets

propagating a fire will typically start

with an electrical arc. Therefore, the

resistance to an arc-tracking KaptonTM

(i.e., polyimide) wire fire should be

assessed. The commenter contends that

this will give a clear indication of what

the next flight crew might experience,

rather than a Bunsen Burner or cotton

swab test that doesn’t relate to the real

world conditions found on affected

airplanes.

The FAA does not concur with the

commenter’s request to include

electrical arcing ignition in the test

procedures. Electrical arc tests were

used to identify the unsafe

characteristics of MPET in the course of

research. The test method required by

this AD is, in fact, a more severe

measure of the materials’ performance.

There are materials that are not

susceptible to ignition by electrical

arcing that will not pass the test

required by this AD. Therefore, the

replacement of MPET insulation

blankets in accordance with this AD

will address the commenter’s concern.

Approved Materials

Two commenters request that the

FAA revise the proposed AD’s to

include an expanded list of approved

films. Several commenters note that

KaptonTM film installed 25 years ago on

Model L–1011 series airplanes has

proven to outperform TedlarTM and

MylarTM films in FAA tests, which

measure the materials’ ability to hold

back flames. Two commenters state that

all FAA testing, including burnthrough

testing, have shown polyimide films to

be superior. In addition, FAA

Administrator, Jane Garvey, specifically

mentioned KaptonTM film as being a

material that would be ‘‘grandfathered

in’’ in an October 14, 1998,

announcement.

Two commenters state that the

proposed AD’s appear to preclude the

use of polyimide (KaptonTM) insulation

Federal Register / Vol. 65, No. 103 / Friday, May 26, 2000 / Rules and Regulations 34331

covering film that has passed the new

Radiant Panel Test.

The FAA does not concur with the

commenters’ request to revise NOTE 4

of the AD to include additional films.

Except for the metallized TedlarTM

cover mentioned in NOTE 4 of the AD,

currently, no other film has successfully

passed the flammability testing in a

manner approved by the Manager, Los

Angeles ACO. However, the FAA is

aware of various film materials that

could be found to be acceptable

replacement materials for MPET. Once

these materials have successfully passed

the flammability testing specified in the

AD, they must be approved by the

Manager, Los Angeles ACO. In addition

to the flammability requirements, the

material must be shown to meet all

other applicable airworthiness

requirements. The FAA Administrator

did make an announcement in October

1998 that KaptonTM would be

‘‘grandfathered,’’ and that the FAA

would not require that material to be

replaced once is was installed.

However, that announcement was made

prior to the issuance of the NPRM for

this final rule. This AD does NOT

require KaptonTM to be replaced once it

is installed; however, it does require

testing and approval of any material,

including KaptonTM.

One commenter requests that the FAA

revise NOTE 4 of the proposed AD’s to

read ‘‘[t]he metallized Tedlar covers

specified in the service bulletins must

be tested to demonstrate compliance

with the requirements of paragraph (c)

of this AD.’’ The commenter disagrees

with the characterization that a

particular cover material is considered

acceptable with the requirements of

paragraph (c) of the proposed AD’s. The

commenter states that the Thermal

Acoustic Task Group, which was

organized by the Fire (Safety) Test

Branch of the FAA Technical Center to

develop the new flammability

requirements, did not begin to discuss

the procedures for demonstrating

compliance until a seminar was held on

September 13 and 14, 1999. Because the

release date of the NPRM’s was before

the seminar, no material could have

been specified to be in compliance with

the requirements of paragraph (c) of the

NPRM’s. The commenter states that, at

the time of publication of the proposed

AD’s, compliance materials and

methods had not yet been submitted

under a Test Plan, conformity

inspection of samples had not been

completed, and properly witnessed

testing had not taken place.

The FAA does not concur with the

commenter’s request to revise NOTE 4

of the AD as it suggests. The material

that is listed in the service bulletins has

been found acceptable by the FAA and

was tested at the FAA Technical Center

in a manner approved by the FAA, prior

to the September seminar. The purpose

of the seminar was not to develop test

methods, but to introduce the method to

the interested segment of the industry.

Therefore, the timing of the seminar has

no bearing on the approval status of the

material. No change to the final rule is

necessary.

Replacement Material Approval

Process

One commenter notes that under the

heading ‘‘Differences Between the

Proposed AD and Service Bulletins’’ in

the preamble of the NPRM’s, it states

‘‘* * * Only one of the two insulation

blanket film materials specified in the

service bulletins has successfully passed

the testing of the ASTM flammability

standard and has been found to be an

acceptable replacement material for the

MPET-covered insulation blankets.

Other film material, such as certain

polyimide and fluoropolymer

composites, also have been successfully

tested to ASTM E648 and could be

found to be acceptable for compliance

with the requirements of this proposed

AD if presented to the FAA for

approval. These materials are not listed

in the service bulletins described

previously.’’ The commenter claims that

the original equipment manufacturer

(OEM) and certain operators are

interpreting this statement as requiring

a full Part Manufacturing Approval

(PMA) and Supplemental Type

Certificate (STC) approval process for

blankets using films not in the

referenced McDonnell Douglas service

bulletins.

One commenter states that other new

materials besides KaptonTM will become

available in the near future for use as

insulation coverings, and that the PMA/

STC process is not designed for nor

suited for purely materials testing. The

commenter contends that using this

process would add a great deal of

unnecessary cost to the current approval

process for new materials. Another

commenter requests that the proposed

AD be revised to include language

describing a clear and abbreviated

approval process for blankets utilizing

new and less flammable materials.

The FAA does not concur with the

commenter’s request to include

language describing the process for

approval of replacement insulation

blankets utilizing new and less

flammable materials. The FAA approval

process of replacing materials/

installations is well established and

known. Design approval can be obtained

by an STC or PMA. It is the

responsibility of the operators and

modifiers to obtain such approvals for

any proposed materials under paragraph

(c) of the AD. The FAA may approve

requests for AMOC’s, such as alternative

blanket installation, under the

provisions of paragraph (e) of this AD if

sufficient data are submitted to

substantiate that such a design change

would provide an acceptable level of

safety.

The FAA has determined that an

adequate supply of approved

replacement materials will be available

to comply with this AD in the time

specified. Operators that choose to

develop new or different materials must

plan accordingly and obtain approval as

previously stated. While the PMA or

STC process may not seem to be cost

effective for some operators, it is the

proper approval method to assure all

airworthiness standards are met.

Insulation Material on Other Aircraft

One commenter is not clear if the

material used today on other Boeing

airplanes is able to pass ASTM E648.

The same commenter also states that the

proposed AD’s require full replacement

of only MPET. The commenter is not

clear what the rationale behind this

decision is.

As discussed in the NPRM’s, these

AD’s are intended to correct an unsafe

condition by replacing MPET insulation

blankets. MPET film differs from other

films in use in that it is susceptible to

propagation of a fire from a small

ignition source. Other films, while not

necessarily meeting the proposed test

requirements, do not have this

susceptibility. It is the susceptibility to

small ignition sources that creates the

unsafe condition. New standards for

insulation materials in general may be

similar to the requirements of this AD,

but will be used to upgrade the level of

safety, and not correct an unsafe

condition.

Burnthrough

Several commenters request that the

FAA revise the proposed AD’s to make

clear that airlines are permitted to

install insulation that meets a

burnthrough protection standard. Two

commenters state that the proposed

AD’s appear to preclude the use of

Curlon as a substitute for fiberglass to

achieve burnthrough performance. One

commenter states that Curlon material

and many other materials recently

developed could easily and

economically provide double the level

of protection of the current burnthrough

time (i.e., four minutes). Although the

proposed AD’s do not address the

34332 Federal Register / Vol. 65, No. 103 / Friday, May 26, 2000 / Rules and Regulations

burnthrough safety threat, the

commenters want to take this

opportunity to achieve this important

safety advance when replacing the

insulation. The commenters

reemphasize that this would simply be

reinforcing the October 1998

announcement that Curlon would be

one of the materials ‘‘grandfathered in,’’

if operators proceeded to install it

voluntarily.

Two commenters request that the

FAA revise the proposed AD’s to

include requirements for burnthrough

protection from fuel fires on the ground

for all affected airplanes. The

commenters state that replacement of

flammable insulation is an opportunity

to install burnthrough protection. One

commenter states that this should be the

time to push the industry, as was done

with the heat release requirements for

interior materials a few years ago.

Materials were not even available to

meet the new FAA requirements, but

the industry ‘‘stepped up to the plate

and we now are all safer as a result of

this proactive approach.’’

The FAA does not concur with the

commenters’ requests to include

burnthrough requirements in the AD.

While burnthrough protection is

important to the overall fire resistance

of airplanes following an accident, the

actions required by this AD are intended

to correct a known unsafe condition—

insulation blankets constructed of

MPET. The FAA does not consider that

the degree of burnthrough protection

provided by currently installed

insulation constitutes an unsafe

condition. Therefore, it would be

inappropriate to issue an AD to require

improvement in burnthrough

protection. The new replacement

insulation blankets required by this AD

meet the test method specified in the

final rule, correct the identified unsafe

condition, and provide the level of

safety required by 14 CFR part 25. The

FAA encourages the installation of

materials that meet additional standards

such as fuselage burnthrough

protection.

Trade Names

One commenter opposes the use of

trade names in both the preamble and

regulatory text of the proposed AD’s and

considers such references to trade

names highly prejudicial to Chemfab,

the manufacturer of Chemfilm. The

commenter states that there is no need

for brand name product identification

and that this connotes not only FAA

approval of, but also preference for, the

identified product brand. Once the

official ‘‘seal of approval’’ has been

granted through the rulemaking process,

other market entrants face a significant

barrier in gaining customer acceptance

simply because the identified product

has been ‘‘officially’’ sanctioned.

Because of the publication and

circulation of the proposed AD’s, two

commenters request that the FAA revise

the proposed AD’s to identify the

manufacturer(s) and trade names of

insulation blanket covering films that

have met FAA requirements specified in

the proposed AD’s.

The FAA does not concur with the

commenters’ request to reference other

trade name products in the final rules or

to eliminate all references. TedlarTM and

MylarTM are common trade names and

this is the clearest way for FAA to

communicate with affected operators.

Except for the one metallized TedlarTM

cover mentioned in NOTE 4 of the AD,

currently, no other film has been

approved by the Manager, Los Angeles

ACO. In addition, the airplane

manufacturer is planning to list

materials, once they have been tested

and approved by the FAA, in the

revised service bulletins (discussed

previously under the heading

‘‘Inadequate Procedures and

Information in Referenced Service

Bulletin’’). Furthermore, the FAA finds

that trade names such as of MylarTM,

KaptonTM, and TedlarTM are well known

and are accepted terminology in

industry. The reference of these trade

names in the AD’s are not, in any way,

an FAA endorsement of those products.

Therefore, no change to the final rule is

necessary.

Wiring

One commenter requests that

flammability requirements for the

sources of ignition (i.e., the wiring) for

thermal blanket fires be stricter than the

requirements for thermal blankets

themselves. The commenter states that

the 60-degree flame test—the only test

required by the FAA for the wiring on

commercial airplanes—should be

replaced immediately with the vertical

flame test as a minimum requirement,

and that every type of wire insulation in

all airplanes should have to meet it.

The FAA does not concur. The

current flammability standard for wiring

has not been determined to be

inadequate. The actions required by this

AD are intended to address an identified

unsafe condition, which is that MPETcovered insulation blankets can

contribute to the spread of a fire when

ignition occurs from a small ignition

source such as electrical arcing or

sparking. As noted previously, the FAA

has a major program underway to

address issues related to airplane wiring

and problems are being addressed as

they are identified.

Corrosion Protection

One commenter states that for Model

MD–11 series airplanes to be afforded

the same corrosion protection offered by

the OEM installation, any fabricated

blankets must meet the original type

design. The existing Corrosion

Prevention and Control Program (CPCP)

requirements are based on the

performance of the insulation system.

Any compromise or alteration will

necessitate changes to the CPCP. Many

insulation blankets cannot be installed

as they originally were due to

installation of overlying structure.

Therefore, deviations to the type design

will have to be approved by the OEM

and FAA in the form of an AMOC. The

burden of these approvals will stress the

resources of the OEM and FAA over the

duration of the compliance period.

The FAA does not concur. The FAA

is aware of the potential effects of

changing insulation material has on the

corrosion protection of the affected

airplanes. The airplane manufacturer

intends to take this into account so that

no change to the CPCP is required. Any

operator or modifier also will be

required, under paragraph (e) of this

AD, to address any ramifications to the

CPCP in any request for an AMOC.

Add New Inspection

One commenter requests that, if it is

determined that an insulation blanket is

not constructed of MPET during the

action required by paragraph (a) of the

proposed AD’s, a visual inspection be

conducted to detect fire damage,

electrical arcing, discoloration, or other

physical damage. The commenter also

requests a visual inspection for possible

ignition sources during routine

maintenance on airplanes not affected

by the proposed AD’s.

The FAA does not concur with the

commenter’s request to revise paragraph

(a) of the final rule to include a visual

inspection for possible ignition sources.

If any evidence of fire damage is found

during the subject inspection, operators

are already required to investigate and

determine the source of the problem.

This is no different from any other

maintenance action that is performed by

the operators. It is not necessary to

include any additional requirements in

this AD to accomplish this action.

Alternative Method of Compliance

One commenter states that it has

developed a system whereby the

existing bagged insulation can be

removed from the airplane without the

necessity of interfering with wiring

Federal Register / Vol. 65, No. 103 / Friday, May 26, 2000 / Rules and Regulations 34333

harnesses or other unrelated systems.

The commenter claims that its system

would reduce the installation time of

the proposed AD’s, reduce the cost of

compliance, and reduce the remote

chances of creating future related AD’s

caused by the method of compliance.

Another commenter states that it also

has developed an insulation system that

works around existing equipment and

thus eliminates the need to remove

much of the equipment that is not

normally removed during heavy

maintenance checks. The commenter

claims that its system is lighter in

weight than the OEM insulation system

and will result in fuel savings.

One commenter agrees that the

flammability/flame spread performance

of the MPET-covered insulation

blankets should be improved, but

questions proposed AD’s that would

require blanket replacement. The

commenter states that this approach

may not be the only possible method of

addressing the issue. This concept is

especially important considering the

potential negative consequences of

required airplane disassembly to

accomplish the blanket replacement.

The commenter suggests that there may

be other options such as spray coatings

that offer virtually equivalent

performance with little negative impact.

From these comments, the FAA infers

that the commenters are requesting that

the final rules be revised to include the

commenter’s systems for replacing or

modifying the MPET insulation

blankets. The FAA does not concur. The

commenters did not provide any

technical details for the FAA to make a

finding. Paragraph (e) of the final rule

contains provisions for requesting

approval of an AMOC to address these

types of unique circumstances.

One commenter requests that the FAA

require installation of additional fire

resistant material(s) between the

insulation blankets and any adjacent

wires, wire bundles, or other potential

ignition sources instead of removing

and replacing MPET insulation

blankets. The commenter also requests

that the FAA consider this approach on

either a full or partial basis. Another

commenter believes that fire resistant

material(s) in such a location would

better promote the overall safety of the

affected airplanes.

The FAA acknowledges that this

suggestion may be a possible acceptable

alternative to removing the existing

insulation blankets. However, no change

to the final rule is necessary. Under

paragraph (e) of the AD, operators may

apply for the approval of an AMOC or

adjustment of the compliance time that

provides an acceptable level of safety.

Communication

One commenter requests that the FAA

have a public meeting regarding the

proposed AD’s. The commenter states

that, because many vendors are trying to

develop materials that meet the new

FAA requirements, and the market price

of these materials seems to vary

drastically at present, it just has

insufficient information on new

materials.

The FAA does not concur that a

public meeting regarding the proposed

AD’s is necessary. Through the FAA

Technical Center, the FAA has provided

a forum to develop flammability

standards for insulation materials. In

addition, the FAA is aware of a number

of meetings hosted by the airplane

manufacturer to provide information to

operators affected by the requirements

of this AD. The FAA is sensitive of the

public’s concern with the fire safety

issues associated with this AD and is

aware of the effects this AD will have on

operators. The FAA has determined that

an unsafe condition exists, and that the

actions required by this AD are

necessary in order to ensure the

continued safety of the affected fleet.

Extend Comment Period of NPRM’s,

Delay Issuance of Final Rules, and

Withdraw NPRM’s

For the reasons described above,

several commenters request that the

FAA do one or more of the following:

(1) Extend the public comment period

for the NPRM’s and supplemental

NPRM’s; (2) delay issuance of the final

rules; or (3) withdraw the NPRM’s and

combine them with the draft

burnthrough NPRM. (The FAA infers

that the commenters are referring to a

draft NPRM relating to insulation

blanket flammability. The FAA

announced its intention to develop new

flammability standards for thermal/

acoustic insulation in October 1998.

This announcement included mention

of improved burnthrough protection.)

One commenter states that it is not

uncommon, in the case of an AD

relating to issues not as complex as the

proposed AD’s, for the FAA to allow 90

days or more to comment. The 45-day

comment period of the proposed AD’s

does not allow for proper understanding

and evaluation on which to develop

reasonable comments.

The FAA does not concur with the

commenters’ request to extend the

comment period. On November 10,

1999, the FAA issued supplemental

NPRM’s to reopen the comment period

for an additional 25 days to provide

opportunity for public comment (the

comment period for the NPRM’s was 45

days and closed on September 27,

1999). The FAA finds that the public

has had a reasonable opportunity to

comment on the substance of the AD’s.

The FAA does not concur with the

commenter’s statement that it is not

uncommon for the FAA to allow 90

days or more for the public to comment

on proposed AD’s. The standard

comment period is 45 days for NPRM’s

and 25 days for supplemental NPRM’s

in which the FAA has responsibility as

the State of Design of the affected

airplanes. A 90-day comment period

would be uncommon.

As discussed above in ‘‘Inadequate

Procedures in Referenced Service

Bulletins,’’ the FAA also finds that it is

possible to accomplish the requirements

of this AD. Since the issuance of the

NPRM’s, the airplane manufacturer, in

conjunction with operators, has

completed the prototype installations.

Based on the results of these

installations, the airplane manufacturer

is developing revisions to the service

bulletins referenced in the AD’s to

include detailed instructions for

accomplishment of the required

replacement. These revised service

bulletins are scheduled for completion

in June 2000. Any new or revised

service bulletins, among other items,

will contain procedures to maintain/test

the integrity of the wiring after

accomplishment of the replacement of

any MPET insulation blanket. These

revised service bulletins will be

approved as an AMOC for the

requirements of this AD.

The FAA does not concur with the

commenter’s request to delay issuance

of the final rules. These revised service

bulletins are scheduled for completion

in June 2000. The FAA has determined

that, while physically challenging, the

actions required by the AD can be

accomplished within the 5-year

compliance time, and that the actions

are warranted to address an identified

unsafe condition.

In support of its request to withdraw

the NPRM’s, one commenter contends

that other rulemaking in development

by the FAA may eventually affect the

airplanes covered by this AD, thereby

requiring two extensive modifications.

The FAA does not concur with the

commenter’s request to withdraw the

NPRM’s and combine them with the

draft burnthrough NPRM. Any other

regulatory action to raise the level of

safety would have to be justified and

subject to public comment. The FAA

does not anticipate requiring airplanes

to be modified twice as a result of future

actions. The actions required by this AD

are intended to correct an identified

unsafe condition by removing MPET

insulation blankets from airplanes

34334 Federal Register / Vol. 65, No. 103 / Friday, May 26, 2000 / Rules and Regulations

affected by these AD’s. These actions are

not intended to provide a general

upgrade to the current level of safety

specified in the airworthiness

regulations. Therefore, the actions

required by these AD’s are warranted.

One commenter disagrees that

prototyping efforts are necessary to

determine the feasibility of the

requirements of the proposed AD’s and

disagrees that issuance of the proposed

AD’s should be delayed. The commenter

states that it is in the process of

prototyping the insulation retrofit on

several affected airplanes. The

commenter expects the prototyping to

be completed in 6 weeks (the

commenter’s letter was received by the

FAA on September 27, 1999). The FAA

concurs with the commenter that

issuance of the final rules should not be

delayed. As discussed previously, the

FAA has participated in the prototyping

specified by the commenter, and that

prototyping effort has been completed.

Cost Estimates

Several commenters state that the

FAA ‘‘grossly’’ underestimated the costs

associated with accomplishing the

requirements of the proposed AD and

provided their cost estimates. Two other

commenters provided cost estimates

that were less than those provided in

the NPRM’s.

The FAA concurs that the cost

estimates specified in the NPRM’s were

underestimated. The FAA based its cost

estimates on information that was

available at the time the NPRM’s were

issued. Since the issuance of the

NPRM’s, the FAA has carefully

reviewed the information and cost

estimates provided by the commenters

and the information obtained during the

prototype exercises. The FAA has

learned that most Model DC–9–80 and

MD–90–30 series airplanes do not have

MPET insulation blankets installed in

the nose section of the airplane. Also, a

number of airplanes do not have MPET

insulation blankets in the fuselage, but

have MPET insulation blankets only on

the air conditioning ducting. The

airplane manufacturer will be making

this information available when the

service bulletins are revised, as

mentioned above. In light of these

findings, the FAA has revised the cost

estimates for the final rules, which is

summarized below under the heading

‘‘Regulatory Evaluation Summary.’’

Several commenters request that the

FAA reevaluate the cost estimates once

the prototype exercises are completed.

As discussed previously, the FAA has

revised the cost estimate of the final

rules based on the prototype exercises.

Several commenters state that the

FAA should consider costs associated

with accomplishing the requirements of

both proposed AD’s (i.e., Rules Dockets

99–NM–161–AD and 99–NM–162–AD) ,

under Title II of the Unfunded Mandates

Reform Act of 1995.

The FAA did consider the total costs

associated with accomplishing the

requirements of both NPRM’s for all

affected airplanes under the heading

‘‘Regulatory Evaluation Summary’’ in

the preamble of the NPRM’s. A copy of

the Preliminary Cost Analysis and

Initial Regulatory Flexibility Analysis

also were included in each docket.

These documents, along with the final

documents, are available for the public

to review.

Conclusion

After careful review of the available

data, including the comments noted

above, the FAA has determined that air

safety and the public interest require the

adoption of the rule with the changes

previously described. The FAA has

determined that these changes will

neither increase the economic burden

on any operator nor increase the scope

of the AD.

Regulatory Evaluation Summary

To determine the regulatory impact of

this AD, the FAA conducted a Final

Cost Analysis and a Final Regulatory

Flexibility Analysis. In addition, the

FAA assessed the impact of this AD on

international trade and determined

whether it must satisfy the requirements

of the Unfunded Mandate Reform Act.

While a summary of these findings is

reported in this preamble, a more

detailed discussion is included in the

Rules Docket for this AD.

Since the publication of the NPRM,

the FAA has observed several prototype

exercises that involved the removal and

replacement of MPET insulation

blankets. Information gained through

these exercises has contributed to

greater understanding by the FAA,

operators, and manufacturer of the

technical details and impacts of the

requirements of this AD.

The FAA took account of the results

of the prototype exercises, comments to

the NPRM’s, and other additional

information, and then adjusted its

estimates of the costs attributable to this

AD. Further, recent information

indicates that the count of affected

airplanes is 621 Model DC–9–80 series

airplanes and 21 Model MD–90–30

series airplanes. Specifics of these

adjustments are discussed below.

Several commenters indicate that the

FAA underestimated the costs of the

new insulation material, labor hours

necessary for retrofitting, and lost

passenger revenue from retrofitting

downtime. With respect to labor and

material costs, the FAA contacted the

major material suppliers (one of which

was the airplane manufacturer) and

three carriers that together operate 75%

of the affected fleet. Information and

estimates from these sources support

increases both in the level of detail and

in the levels of labor and material costs

for this adjusted estimate. Therefore, the

labor cost calculation methods used in

this AD differ from those used in the

NPRM’s. The FAA has developed the

labor estimates for this AD using

information supplied by the

manufacturer and affected operators to

arrive at average values specific to the

requirements of this AD. The FAA

considers these values conservative.

The commenters express

disagreement with the asset-based

approach the FAA used in the

Preliminary Cost Analysis to estimate

the cost of the loss of service of the

airplanes during their retrofits. The

commenters suggest that the estimate be

made on the basis of loss of per seat

revenue. There are two reasons why the

FAA uses the asset-based approach.

First, the FAA takes an industry-wide

perspective in which a passenger who

cannot be seated on an airplane that is

out of service for compliance with this

AD can be seated on an airplane that is

in service. On an industry-wide basis,

no revenue will be lost. Second, the

contribution of a seat’s revenue to

corporate net income is subject to

variations in accounting, financial,

marketing, and operational practice.

The FAA’s asset-based approach

centers on the financial ratio, overall

corporate rate of return, which was

reported by the operators and published

by the Department of Transportation.

This ratio is applied to the average value

of the assets lost to the service of the

operators and is adjusted for the average

period of time for which they are lost

because of compliance. This approach

assumes that operators maximize the

value of their firms by optimizing the

mix and quantity of their assets.

Even though the FAA uses essentially

the same ‘‘lost-revenue’’ method as that

in the supplemental NPRM’s, the FAA

nevertheless did increase its estimates

of lost revenue by increasing the

number of days out of service, reducing

the operating base year from 365 days to

approximately 320 days, and raising the

rate of return (9% is an average of

domestic passenger and cargo operators’

profit rates as estimated by the

Department of Transportation’s Bureau

of Transportation Statistics). All of these

adjustments raise the value of the

Federal Register / Vol. 65, No. 103 / Friday, May 26, 2000 / Rules and Regulations 34335

variables applied to the airplane asset

values (i.e., $16.2 million per DC–9–80/

MD–90–30).

The FAA has identified 621 Model

DC–9–80 and 21 MD–90–30 series

airplanes that will be subject to

retrofitting. Four of these airplanes have

MPET insulation installed throughout.

Thirty-five of these airplanes have

MPET insulation installed only around

air conditioning ducts. Six hundred and

three of these airplanes have MPET

installed throughout except for the nose.

These patterns of installation strongly

affect the retrofitting costs for each

individual airplane. The FAA final costs

estimate reflects the cost of each

airplane when averaged for the total

DC–9–80/MD–90–30 affected fleet.

The foregoing results in the following

adjustments to the calculations

presented in the supplemental NPRM.

For Model DC–9–80 series airplanes,

the preliminary estimates for labor,

material, and lost service per airplane

were as follows: labor, $335,988;

material, $27,021; and lost service,

$20,416. The corresponding MD–90–30

estimates were as follows: $385,560;

$31,008; and $37,052.

The components of this adjusted

estimate per airplane, for both Model

DC–9–80 and MD–9–30 series airplanes,

are as follows: combined labor and

material, $479,921 (averaged as

$628,184 for 4 airplanes, $73,156 for 35

airplanes, and $502,547 for 603

airplanes, as discussed above); and lost

service, $65,998. Overall, the adjusted

estimates compare to the original

estimates as follows:

Original Adjusted

625 DC–9–80, each

$383,000.

621 MD80s, each

$545,919.

22 MD–90–30, each

$454,000.

21 MD90s, each

$545,919.

The adjusted estimate of the total

costs of this AD over the five-year

retrofit period for all 644 affected

narrow-body airplanes is approximately

$351.6 million or $288.6 million

discounted to present value. The total

impact for all affected airplanes (i.e.,

Model DC–9–80, MD–90–30 , MD–11,

and DC–10 series airplanes) is 449.3

million or 368.4 million discounted to

present value over the five year

compliance time.

With respect to effects on small

entities, the Regulatory Flexibility Act

(RFA) of 1980 establishes ‘‘as a

principle of regulatory issuance’’ that

agencies shall endeavor, consistent with

the objective of the rule and of

applicable statutes, to fit regulatory and

informational requirements to the sale

of the business, organizations, and

governmental jurisdictions subject to

regulation. To achieve that principle,

the RFA requires agencies to solicit and

consider flexible regulatory proposals

and to explain the rationale for their

actions. The RFA covers a wide range of

small entities, including small

businesses, not-for-profit organizations,

and small governmental jurisdictions.

Agencies must perform a review to

determine whether a proposed or final

rule will have a significant economic

impact on a substantial number of small

entities. If the determination is that it

will, the Agency must prepare a

regulatory flexibility analysis as

described in the RFA. However, if an

agency determines that a proposed or

final rule is not expected to have a

significant economic impact on a

substantial number of small entities,

section 605(b) of the RFA provides that

the head of the agency may so certify

and a regulatory flexibility analysis is

not required. The certification must

include a statement providing the

factual basis for this determination, and

the reasoning should be clear.

Of the operators affected by this AD,

all but three are air carriers, none of

which is a small business. In two of the

remaining cases, Model DC–9–80 series

airplanes are owned for personal use.

One Model DC–9–80 series airplane is

operated for non-carrier business

purposes by a large corporation.

Although the small business size

criterion is met in the cases of the two

Model DC–9–80 series airplanes that are

owned for personal use, two such

entities do not constitute a ‘‘substantial

number’’ within the meaning of the

RFA. Thus, pursuant to the Regulatory

Flexibility Act, 5 U.S. C. 605(b), the

FAA certifies that this AD will not have

a significant economic impact on a

substantial number of small entities.

The provisions of this AD will have

little or no impact on trade for U.S.

firms doing business in foreign

countries and foreign firms doing

business in the United States.

Finally, Title II of the Unfunded

Mandates Reform Act of 1995 (the Act),

enacted as Public Law 104–4 on March

22, 1995, requires each Federal agency,

to the extent permitted by law, to

prepare a written assessment of the

effects of any Federal mandate in a

proposed or final agency rule that may

result in the expenditure by State, local,

and tribal governments, in the aggregate,

or by the private sector, of $100 million

or more (adjusted annually for inflation)

in any one year. Section 204(a) of the

Act, 2 U.S.C. 1534, requires the Federal

agency to develop an effective process

to permit timely input by elected

officers (or their designees) of State,

local, and tribal governments on a

proposed ‘‘significant intergovernmental

mandate.’’ A ‘‘significant

intergovernmental mandate’’ under the

Act is any provision in a Federal agency

regulation that would impose an

enforceable duty upon State, local, and

tribal governments, in the aggregate, of

$100 million (adjusted annually for

inflation) in any one year. Section 203

of the Act, 2 U.S.C. 1533, provides that

before establishing any regulatory

requirements that might significantly or

uniquely affect small governments, the

agency shall have developed a plan that,

among other things, provides for notice

to potentially affected small

governments, if any, and for a

meaningful and timely opportunity to

provide input in the development of

regulatory proposals.

This AD does not contain any Federal

intergovernmental or private sector

mandate. Therefore, the requirements of

Title II of the Unfunded Mandates

Reform Act of 1995 do not apply.

List of Subjects in 14 CFR Part 39

Air transportation, Aircraft, Aviation

safety, Incorporation by reference,

Safety.

Adoption of the Amendment

Accordingly, pursuant to the

authority delegated to me by the

Administrator, the Federal Aviation

Administration amends part 39 of the

Federal Aviation Regulations (14 CFR

part 39) as follows:

PART 39—AIRWORTHINESS

DIRECTIVES

1. The authority citation for part 39

continues to read as follows:

Authority: 49 U.S.C. 106(g), 40113, 44701.

§ 39.13 [Amended]

2. Section 39.13 is amended by

adding the following new airworthiness

directive:

2000–11–01 McDonnell Douglas:

Amendment 39–11749. Docket 99–NM–

161–AD.

Applicability: Model DC–9–81 (MD–81),

DC–9–82 (MD–82), DC–9–83 (MD–83), DC–

9–87 (MD–87) series airplanes; Model MD–

90–30 series airplanes; and Model MD–88

airplanes; manufacturer’s fuselage numbers

995 through 2243 inclusive; certificated in

any category.

Note 1: This AD applies to each airplane

identified in the preceding applicability

provision, regardless of whether it has been

modified, altered, or repaired in the area

subject to the requirements of this AD. For

airplanes that have been modified, altered, or

repaired so that the performance of the

requirements of this AD is affected, the

34336 Federal Register / Vol. 65, No. 103 / Friday, May 26, 2000 / Rules and Regulations

owner/operator must request approval for an

alternative method of compliance in

accordance with paragraph (e) of this AD.

The request should include an assessment of

this AD; and, if the unsafe condition has not

been eliminated, the request should include

specific proposed actions to address it.

Compliance: Required as indicated, unless

accomplished previously.

To ensure that insulation blankets

constructed of metallized

polyethyleneteraphthalate (MPET) are

removed from the fuselage, accomplish the

following:

Inspection

(a) Within 5 years after the effective date

of this AD, determine whether, and at what

locations, insulation blankets constructed of

MPET, are installed. When markings are not

visible, the determination shall be made by

using known MPET material as a comparison

sample to assist in the identification.

Note 2: Insulation blankets that are marked

with ‘‘DMS 2072, Type 2, Class 1, Grade A;’’

‘‘DMS 2072, Type 2, Class 1;’’ or ‘‘DMS 1996,

Type 1;’’ are constructed of MPET.

Corrective Actions

(b) For insulation blankets that are

determined not to be constructed of MPET,

no further action is required by this AD.

(c) For insulation blankets that are

determined to be constructed of MPET,

within 5 years after the effective date of this

AD, replace the MPET insulation blankets

with new insulation blankets that have been

approved by the Manager, Los Angeles

Aircraft Certification Office (ACO), FAA,

Transport Airplane Directorate. The blankets

shall be replaced in accordance with the

Accomplishment Instructions of McDonnell

Douglas Service Bulletin MD–90–25–015,

Revision 01, dated November 5, 1997 (for

Model MD–90–30 series airplanes); or

McDonnell Douglas Service Bulletin MD80–

25–355, Revision 01, dated November 5, 1997

(for Model DC–9–80 series airplanes and

Model MD–88 airplanes); as applicable. The

replacement insulation blankets must be

constructed of materials tested in accordance

with Appendix 1 of this AD, or in accordance

with a method approved by the Manager, Los

Angeles ACO.

Note 3: Although this paragraph allows up

to 5 years for the required replacement, the

FAA anticipates that operators will comply at

the earliest practicable maintenance

opportunity.

Note 4: Only one of the two metallized

TedlarTM covers specified in the service

bulletins has been shown to have

successfully passed the testing of the

American Society for Testing and Materials

(ASTM) flammability standard and is

considered acceptable for compliance with

the requirements of paragraph (c) of this AD.

Spares

(d) As of the effective date of this AD, no

person shall install an MPET insulation

blanket on any airplane.

Alternative Methods of Compliance

(e) An alternative method of compliance or

adjustment of the compliance time that

provides an acceptable level of safety may be

used if approved by the Manager, Los

Angeles ACO. Operators shall submit their

requests through an appropriate FAA PMI,

who may add comments and then send it to

the Manager, Los Angeles ACO.

Note 5: Information concerning the

existence of approved alternative methods of

compliance with this AD, if any, may be

obtained from the Los Angeles ACO.

Special Flight Permits

(f) Special flight permits may be issued in

accordance with sections 21.197 and 21.199

of the Federal Aviation Regulations (14 CFR

21.197 and 21.199) to operate the airplane to

a location where the requirements of this AD

can be accomplished.

Incorporation by Reference

(g) The blankets shall be replaced in

accordance with the Accomplishment

Instructions of McDonnell Douglas Service

Bulletin MD–90–25–015, Revision 01, dated

November 5, 1997; or McDonnell Douglas

Service Bulletin MD80–25–355, Revision 01,

dated November 5, 1997; as applicable. This

incorporation by reference was approved by

the Director of the Federal Register in

accordance with 5 U.S.C. 552(a) and 1 CFR

part 51. Copies may be obtained from Boeing

Commercial Aircraft Group, Long Beach

Division, 3855 Lakewood Boulevard, Long

Beach, California 90846, Attention: Technical

Publications Business Administration, Dept.

C1–L51 (2–60). Copies may be inspected at

the FAA, Transport Airplane Directorate,

1601 Lind Avenue, SW., Renton,

Washington; or at the FAA, Transport

Airplane Directorate, Los Angeles Aircraft

Certification Office, 3960 Paramount

Boulevard, Lakewood, California; or at the

Office of the Federal Register, 800 North

Capitol Street, NW., suite 700, Washington,

DC.

(h) This amendment becomes effective on

June 30, 2000.

Appendix 1.—Test for Materials

Replacing Metallized PET Thermal

Acoustical Insulation, Film February

16, 2000

This test method is used to evaluate the

flammability and flame propagation

characteristics of thermal/acoustic insulation

when exposed to both a radiant heat source

and a flame.

(a) Definitions.

(1) Thermal/Acoustic Insulation. Thermal/

acoustic insulation is defined as a material or

system of materials used to provide thermal

and/or acoustic protection. Examples include

a film-covering material encapsulating a core

material such as fiberglass or other batting

material and foams.

(2) Radiant Heat Source. The radiant heat

source is an air/gas fueled radiant heat

energy panel.

(b) Test Apparatus (as schematically

shown in figure 1).

(1) Radiant Panel Test Chamber. Tests will

be conducted in the radiant panel test

chamber as used in ASTM—Designation: E

648. It is suggested that the test chamber be

located under an exhaust hood to facilitate

clearing the chamber of smoke after each test.

The radiant panel test chamber shall consist

of an enclosure 55 inches (1400 mm) long by

191⁄2 inches (500 mm) deep by 28 inches (710

mm) above the test specimen. The sides,

ends, and top shall be insulated with a

fibrous ceramic insulation such as

KaowoolTM board. One side shall be provided

with an approximately 48 by 6 inch (1219 by

152mm) draft tight, high temperature, heat

resistant glass observation window, to

facilitate viewing the sample during testing.

On the same side and below the window is

a door which, when open, allows the

specimen platform to be moved out for

mounting or removal of test specimens. The

bottom of the test chamber shall consist of a

sliding steel platform, which has provisions

for securing the test specimen holder in a

fixed and level position. The top of the

chamber shall have an exhaust stack with

interior dimensions of 4 inches (102mm)

wide by 15 inches (380 mm) deep by 12.5

inches (318mm) high at the opposite end of

the chamber from the radiant energy source.

(2) Radiant Heat Source. The radiant heat

energy source will be a panel of porous

refractory material mounted in a cast iron

frame, with a radiation surface of 12 by 18

inches (305 by 457mm). It shall be capable

of operating at temperatures up to 1500°F

(816°C (Figure 1).

Federal Register / Vol. 65, No. 103 / Friday, May 26, 2000 / Rules and Regulations 34337

(i) Radiant Panel Fuel System. The radiant

panel fuel will be propane (liquid petroleum

gas—2.1 UN 1075). The panel fuel system

shall consist of a venturi-type aspirator for

mixing gas and air at approximately

atmospheric pressure. Suitable

instrumentation will be necessary for

monitoring and controlling the flow of fuel

and air to the panel. Instrumentation will

include an air flow gauge, an air flow

regulator, a gas pressure gauge, and a

rotameter for measuring gas flow.

(ii) Radiant Panel Placement. The panel

will be mounted in the chamber at 30 degrees

to the horizontal specimen plane.

(3) Specimen Holding System.

(i) The sliding platform serves as the

housing for test specimen placement. A 1⁄4

inch (6.35mm) sheet of Durarocκa

 ̈

, or other

non-combustible base, measuring 431⁄4

inches by 121⁄2 inches (1098 by 317.5mm)

will be placed in the open bottom (base) of

the sliding platform. It is necessary to cut the

non-combustible base into two pieces for

placement in the bottom of the platform,

since it will be supported by a 3⁄4-inch

(19.1mm) lip that extends around the bottom

of the platform base. It is suggested that the

shortest piece be placed at the end furthest

from the radiant panel (figure 2). A 1⁄2 inch

(13mm) piece of KaowooλTM board or other

high temperature material measuring 411⁄2 by

81⁄4 inches (1054 by 210mm) will be attached

to the back side of the platform. This board

will serve as a heat retainer and will protect

the test specimen from excessive preheating.

The height of this board must not be too high

such that it will impede the sliding platform

movement (in and out) of the test chamber.

34338 Federal Register / Vol. 65, No. 103 / Friday, May 26, 2000 / Rules and Regulations

(ii) The test specimen will be placed

horizontally on the non-combustible base. A

stainless steel retaining frame (AISI Type 300

UNA–NO8330), or equivalent, having a

thickness of 0.078 inches (1.98mm) and

overall dimensions of 443⁄4 by 123⁄4 inches

(1137 by 320mm) with a specimen opening

of 40 by 77⁄8 (1016 by 140mm) will be placed

on top of the test specimen. The retaining

frame will have two 1⁄2inch (12.7mm) holes

drilled at each end for positioning the frame

to the two stud bolts at each end of the

sliding platform (figure 3).

(iii) A securing frame (acting as a clamping

mechanism) constructed of mild steel will be

placed over the test specimen. The securing

frame overall dimensions are 421⁄2 by 101⁄2

inches (1080 by 267mm) with a specimen

opening of 391⁄2 by 71⁄2 inches (1003 by

190mm). Hence, the exposed area of test

specimen exposed to the radiant panel is

391⁄4 by 71⁄4 inches (996 by 184mm). See

figure 4. It is not necessary to physically

fasten the securing frame over the test

specimen due to the weight of the frame

itself.

(4) Pilot Burner. The pilot burner used to

ignite the specimen is a commercial propane

venturi torch with an axially symmetric

burner tip having a propane supply tube with

an orifice diameter of 0.003 inches

(0.076mm). The propane flow is adjusted to

produce a pencil flame blue inner cone

length of 1⁄2 inch (13mm). There will be a

means provided to move the burner out of

the ignition position so that the flame is

horizontal and at least 2 inches (50mm)

above the specimen plane.

(5) Thermocouples. Three 24 American

Wire Gauge (AWG) Type K (ChromelAlumel) thermocouples will be installed in

the test chamber for temperature monitoring.

All three are inserted into the chamber

through three small holes drilled through the

top of the chamber. One thermocouple is

placed 2 inches (51mm) from the end of the

radiant panel and approximately 16 inches

(406mm) above the test specimen. The

second thermocouple is placed 5 inches

(127mm) from the first thermocouple and

approximately 16 inches (406mm) from the

sample. The third thermocouple is located in

the chimney approximately 38 inches

(965mm) above the specimen.

(6) Calorimeter. The calorimeter will be a

one inch cylindrical water-cooled, total heat

flux density, foil type Gardon Gage that has

Federal Register / Vol. 65, No. 103 / Friday, May 26, 2000 / Rules and Regulations 34339

a range of 0 to 5 BTU/ft2-second (0 to 5.6

Watts/cm2).

(7) Calorimeter Calibration Specification

and Procedure.

(i) Calorimeter Specification.

(A) Foil diameter will be 0.25±0.005 inches

(6.35±0.13mm).

(B) Foil thickness will be 0.0005±0.0001

inches (0.013±0.0025mm).

(C) Foil material will be thermocouple

grade Constantan.

(D) Temperature measurement will be a

Copper Constantan thermocouple.

(E) The copper center wire diameter will be

0.0005 inches (0.013mm).

(F) The entire face of the calorimeter will

be lightly coated with ‘‘Black Velvet’’ paint

having an emissivity of 96 or greater.

(ii) Calorimeter Calibration.

(A) The calibration method will be by

comparison to a like standardized transducer.

(B) The standardized transducer will meet

the specification given in paragraph (6).

(C) It will be calibrated against a primary

standard by the National Institute of

Standards and Technology (NIST).

(D) The method of transfer will be a heated

graphite plate.

(E) The graphite plate will be electrically

heated, have a clear surface area on each side

of the plate of at least 2 by 2 inches (51 by

51mm), and be 1⁄8 inch ±1⁄16 inch thick (3.2

±1.6mm).

(F) The 2 transducers will be centered on

opposite sides of the plates at equal distances

from the plate.

(G) The distance of the calorimeter to the

plate will be no less than 0.0625 inches

(1.6mm), nor greater than 0.375 inches

(9.5mm).

(H) The range used in calibration will be

at least 0–3.5 BTUs/ft2 second (0–3.9 Watts/

cm2) and no greater than 0–5.6 BTUs/ft2

second (0–5 Watts/cm2).

(I) The recording device used must record

the 2 transducers simultaneously or at least

within 1⁄10 second of each other.

(8) Calorimeter Fixture. With the sliding

platform pulled out of the chamber, install a

2-rail fixture that has a travel range of 401⁄4

inches (1022mm) over the sliding platform.

The dimension between the 2 rails is 211⁄16

inches (68mm). The rail fixture is screwed

into the sliding panel, such that it is always

directly under the geometric center of the

radiant panel (figure 4). Push the platform

into the chamber and insert the calorimeter.

The calorimeter, which is mounted in an

insulated housing, fits in the rail opening but

has enough clearance such that it may be

moved along the rail for heat flux readings.

The top surface of the calorimeter must be

level with the rails.

(9) Instrumentation. A calibrated recording

device with an appropriate range or a

computerized data acquisition system will be

provided to measure and record the outputs

of the calorimeter and the thermocouples.

The data acquisition system must be capable

of recording the calorimeter output every

second.

(10) Timing Device. A stopwatch or other

device, accurate to ±1second/hour, will be

provided to measure the time of application

of the pilot burner flame.

(c) Test Specimens.

(1) Specimen Preparation. A minimum of

three test specimens will be prepared and

tested.

(2) Construction. Cut a piece of core

material such as foam or fiberglass. If

fiberglass is used, cut the material 431⁄2 (±1⁄4)

inches long (1093mm) (±6.3mm) by 121⁄2

inches (305.1mm) wide. If using foam, cut

the material 411⁄4 inches (1039mm) by 11

inches wide (279mm) by 11⁄2 inches (381mm)

high. Cut a piece of film cover material (if

used) large enough to cover the core material.

It is permissible to staple the film cover at

the ends, as they are not exposed to the

radiant heat source. A piece or pieces of an

inorganic/inert material such as KaowooλTM

or Marinitε TM board may be placed in the

bottom of the sliding platform holder if the

sample is not thick enough to be level with

the top of the sliding platform. The specimen

thickness must be of the same thickness as

installed in the airplane.

(d) Specimen Conditioning. The specimens

will be conditioned at 70 ±5°F (21 ±2°C) and

55%±10% relative humidity for a minimum

of 24 hours prior to testing.

(e) Calibration.

(1) With the sliding platform out of the

chamber, install the rail fixture. Push the

platform back into the chamber, install the

calorimeter (in its housing), and move the

calorimeter to the ‘‘zero’’ position (figure 5).

Close the bottom door located below the

sliding platform. The centerline of the

calorimeter is 17⁄8 inches (46mm) from the

end of the sliding platform. This will be the

‘‘zero’’ position. The distance from the center

of the calorimeter to the radiant panel surface

at this point is 7.5 inches ±1⁄8 (191 mm ±3).

(i) Prior to igniting the radiant panel,

ensure that the calorimeter face is clean and

that there is water running through the

calorimeter.

(2) Ignite the panel. Adjust the fuel/air

mixture to achieve 1.5 BTUs/ft2–second

±0.025 BTUs/ft2–second (1.9 Watts/

cm2±0.025 Watts/cm2) at the ‘‘zero’’ position.

Allow the unit to reach steady state (this may

take up to 1 hour). The pilot burner is off

during this time. The temperature as

measured by the thermocouple closest to the

panel (forward) is approximately 1100°F

(600°C). The temperatures recorded by

thermocouples 2 and 3 ( thermocouple 3

located in chimney) are approximately 430°F

(230°C) and 300°F (135°C), respectively.

34340 Federal Register / Vol. 65, No. 103 / Friday, May 26, 2000 / Rules and Regulations

(3) After steady-state conditions have been

reached, move the calorimeter 2 inches

(51mm) from the ‘‘zero’’ position and record

the heat flux. Allow a minimum of 30

seconds at each position for the calorimeter

to stablize. Record at least 10 positions.

(Figure 6 depicts a calibration profile.)

(4) It is not necessary to run a full heat flux

calibration (minimum of 10 positions) each

time the chamber is powered on. It is

required that a heat flux measurement be

taken at the ‘‘zero’’ position at the start of the

test period (e.g., each morning) to ensure that

the 1.5 BTU/ft2–second (1.9 Watts/cm2)

requirement be met. A full calibration should

be run periodically.

(5) Open the bottom door, pull out the

sliding platform, and remove the calorimeter

and rail fixture.

(f) Test Procedure.

(1) Ignite the pilot burner. Ensure that it is

at least 2 inches (51mm) above the top of the

platform. The burner must not contact the

specimen until the test begins.

(2) Place the test specimen in the sliding

platform holder. Ensure that the test sample

surface is level with the top of the platform.

At ‘‘zero’’ point, the specimen surface is 71⁄2

inches ±1/8 (191mm ±3) below the radiant

panel.

(3) With film/fiberglass assemblies, it may

be necessary to puncture small holes in the

film cover to purge any air inside. This

allows the operator to maintain the proper

test specimen position (level with the top of

the platform). The holes should be made in

the sides and/or the corners of the test

specimen using a needle-like tool.

(4) Place the retaining frame and the

securing frame over the test specimen.

(5) A small mark should be placed on the

‘‘zero’’ point.

(6) Immediately push the sliding platform

into the chamber and close the bottom door.

(7) Bring the pilot burner flame into

contact with the center of the specimen such

that the center line of the flame impinges on

the ‘‘zero’’ point and simultaneously start the

timer. The burner flame impinges the sample

at an angle of approximately 20 degrees with

the horizontal (front of the sliding platform).

(8) Leave the burner in position for 15

seconds and then remove to a position at

least 2 inches (51mm) above the specimen.

(g) Report.

(1) Identify and describe the specimen

being tested.

(2) Report any shrinkage or melting of the

test specimen.

(3) Report the Burn length

(4) Report Extinguishing Time

(h) Requirements.

(1) During burner application, no flaming

is allowed to propagate more than 2 inches

(50.8mm) along the sample (to the left in

figure 1) of the centerline of the flame.

(2) There shall be no flaming of the test

sample after pilot burner removal.

Federal Register / Vol. 65, No. 103 / Friday, May 26, 2000 / Rules and Regulations 34341

Issued in Renton, Washington, on May 19,

2000.

John J. Hickey,

Manager, Transport Airplane Directorate,

Aircraft Certification Service.

[FR Doc. 00–13149 Filed 5–25–00; 8:45 am]

BILLING CODE 4910–13–P

DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 99–NM–162–AD; Amendment

39–11750; AD 2000–11–02]

RIN 2120–AA64

Airworthiness Directives; McDonnell

Douglas Model DC–10–10F, DC–10–15,

DC–10–30, DC–10–30F, and DC–10–40

Series Airplanes, and Model MD–11

and –11F Series Airplanes

AGENCY: Federal Aviation

Administration, DOT.

ACTION: Final rule.

SUMMARY: This amendment adopts a

new airworthiness directive (AD),

applicable to certain McDonnell

Douglas Model DC–10–10F, DC–10–15,

DC–10–30, DC–10–30F, and DC–10–40

series airplanes, and Model MD–11 and

–11F series airplanes, that requires a

determination be made of whether, and

at what locations, metallized

polyethyleneteraphthalate (MPET)

insulation blankets are installed, and

replacement of MPET insulation

blankets with new insulation blankets.

This amendment is prompted by reports

of in-flight and ground fires on certain

airplanes manufactured with insulation

blankets covered with MPET, which

may contribute to the spread of a fire

when ignition occurs from small

ignition sources such as electrical arcing

or sparking. The actions specified by

this AD are intended to ensure that

insulation blankets constructed of

MPET are removed from the fuselage.

Such insulation blankets could

propagate a small fire that is the result

of an otherwise harmless electrical arc

and could lead to a much larger fire.

DATES: Effective June 30, 2000.

The incorporation by reference of

certain publications listed in the

regulations is approved by the Director

of the Federal Register as of June 30,

2000.

ADDRESSES: The service information

referenced in this AD may be obtained

from Boeing Commercial Aircraft

Group, Long Beach Division, 3855

Lakewood Boulevard, Long Beach,

California 90846, Attention: Technical

Publications Business Administration,

Dept. C1–L51 (2–60). This information

may be examined at the Federal

Aviation Administration (FAA),

Transport Airplane Directorate, Rules

Docket, 1601 Lind Avenue, SW.,

Renton, Washington; or at the FAA,

Transport Airplane Directorate, Los

Angeles Aircraft Certification Office,

3960 Paramount Boulevard, Lakewood,

California; or at the Office of the Federal

Register, 800 North Capitol Street, NW.,

suite 700, Washington, DC.

FOR FURTHER INFORMATION CONTACT:

Robert Stacho, Aerospace Engineer,

Systems and Equipment Branch, ANM–

130L, FAA, Transport Airplane

Directorate, Los Angeles Aircraft

Certification Office, 3960 Paramount

Boulevard, Lakewood, California

90712–4137; telephone (562) 627–5334;

fax (562) 627–5210.

SUPPLEMENTARY INFORMATION: A

proposal to amend part 39 of the Federal

Aviation Regulations (14 CFR part 39) to

include an airworthiness directive (AD)

that is applicable to certain McDonnell

Douglas Model DC–10–30 and –30F

series airplanes, and Model MD–11 and

–11F series airplanes was published as

a notice of proposed rulemaking

(NPRM) in the Federal Register on

August 12, 1999 (64 FR 43963). A

second proposal that was identical to

the NPRM, except that it affected

additional airplanes, was published as a

supplemental NPRM on November 17,

1999 (64 FR 62615). Those actions

proposed to require that a determination

be made of whether, and at what

locations, metallized

polyethyleneteraphthalate (MPET)

insulation blankets are installed, and

replacement of MPET insulation

blankets with new insulation blankets.

Since the issuance of those NPRM’s,

the FAA has observed several

prototyping exercises that involved the

removal and replacement of MPET

insulation blankets. The information

obtained from these exercises assisted

the FAA, operators, and manufacturer in

understanding the technical details and

impact of the requirements of this AD.

Certain aspects of these prototype

exercises will be discussed in the FAA’s

response to the comments received from

the NPRM’s.

Comments

Interested persons have been afforded

an opportunity to participate in the

making of this amendment. Due

consideration has been given to the

comments received.

The FAA has received comments in

response to the NPRM’s and

supplemental NPRM’s to Rules Docket

No.’s. 99–NM–161–AD [applicable to

certain McDonnell Douglas Model DC–

9–81 (MD–81), DC–9–82 (MD–82), DC–

9–83 (MD–83), DC–9–87 (MD–87) series

airplanes; Model MD–90–30 series

airplanes; and Model MD–88 airplanes]

and 99–NM–162–AD (applicable to

certain McDonnell Douglas Model DC–

10–30 and –30F series airplanes, and

Model MD–11 and –11F series

airplanes). Because in most cases the

issues raised by the commenters are

generally relevant to both NPRM’s, each

final rule includes a discussion of all

comments received.

Support for Proposed AD’s

Several commenters support the

intent of the proposed AD’s; however,

they request that some changes be made

(discussed later).

Unsafe Condition

One commenter states that, because

the MPET insulation blankets only

propagate the flame and are not the

source of the flame, the proposed AD’s

should address the unsafe condition

(i.e., source of the flame) rather than

previously certified material (which met

the flammability standard at one time)

that is not creating the unsafe condition.

The FAA does not concur. MPET

insulation blankets, when ignited from

a small ignition source, such as an

electrical arc, can contribute to the

spread of a fire. Such insulation

blankets could propagate a small fire

and lead to a much larger fire. Potential

ignition sources exist in many areas of

the affected airplanes. It is extremely

difficult to determine where all

potential ignition sources are. To

provide the level of safety that is

expected by the public for transport

category airplanes, insulation blankets

constructed of MPET must be removed.

Therefore, the FAA finds that it has

properly identified the unsafe condition

(i.e., insulation blankets constructed of

MPET) addressed by these AD’s.

The same commenter suggests that the

subject blankets be handled as ‘‘attrition

replacements,’’ as intended in the

original McDonnell Douglas service

bulletins. The commenter states that,

since cabin interior flammability has

been addressed already to a large extent

by the FAA, MPET insulation blankets

could be treated comparably, and thus,

integrated into the overall interior

materials requirements. (The FAA infers

that the commenter is referring to the

provisions in 14 CFR section 121.312

related to ‘‘substantially complete

replacement of the cabin interior.’’)

These requirements not only mandate

stricter new standards, but allow older

airplane interiors to remain in service