This section of the FEDERAL REGISTER

contains notices to the public of the proposed

issuance of rules and regulations. The

purpose of these notices is to give interested

persons an opportunity to participate in the

rule making prior to the adoption of the final

rules.

Proposed Rules Federal Register

14231

Vol. 60, No. 51

Thursday, March 16, 1995

DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 94–NM–211–AD]

Airworthiness Directives; Learjet

Model 24, 25, 31, 35, 36, and 55 Series

Airplanes, and Learjet Model 28 and 29

Airplanes

AGENCY: Federal Aviation

Administration, DOT.

ACTION: Notice of proposed rulemaking

(NPRM).

SUMMARY: This document proposes the

supersedure of an existing airworthiness

directive (AD), applicable to certain

Learjet Model 24, 25, 31, 35, 36, and 55

series airplanes, and Learjet Model 28

and 29 airplanes, that currently requires

a revision to the Limitations Section of

the FAA-approved Airplane Flight

Manual (AFM) to prohibit flight above

an altitude of 41,000 feet. The actions

specified by that AD are intended to

prevent cracking and subsequent failure

of the outflow/safety valves, which

could result in rapid decompression of

the airplane. This action would require

replacement of certain outflow/safety

valves, which, when accomplished,

constitutes terminating action for the

previously required AFM limitation.

DATES: Comments must be received by

May 8, 1995.

ADDRESSES: Submit comments in

triplicate to the Federal Aviation

Administration (FAA), Transport

Airplane Directorate, ANM–103,

Attention: Rules Docket No. 94–NM–

211–AD, 1601 Lind Avenue, SW.,

Renton, Washington 98055–4056.

Comments may be inspected at this

location between 9 a.m. and 3 p.m.,

Monday through Friday, except Federal

holidays.

The service information referenced in

the proposed rule may be obtained from

Allied Signal, Inc., Controls &

Accessories, 11100 N. Oracle Road,

Tucson, Arizona 85737–9588; telephone

(602) 469–1000. This information may

be examined 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.

FOR FURTHER INFORMATION CONTACT:

Walter Eierman, Aerospace Engineer,

Systems and Equipment Branch, ANM–

130L, FAA, Transport Airplane

Directorate, Los Angeles Aircraft

Certification Office, 3960 Paramount

Boulevard, Lakewood, California 90712;

telephone (310) 627–5336; fax (310)

627–5210.

SUPPLEMENTARY INFORMATION:

Comments Invited

Interested persons are invited to

participate in the making of the

proposed rule by submitting such

written data, views, or arguments as

they may desire. Communications shall

identify the Rules Docket number and

be submitted in triplicate to the address

specified above. All communications

received on or before the closing date

for comments, specified above, will be

considered before taking action on the

proposed rule. The proposals contained

in this notice may be changed in light

of the comments received.

Comments are specifically invited on

the overall regulatory, economic,

environmental, and energy aspects of

the proposed rule. All comments

submitted will be available, both before

and after the closing date for comments,

in the Rules Docket for examination by

interested persons. A report

summarizing each FAA-public contact

concerned with the substance of this

proposal will be filed in the Rules

Docket.

Commenters wishing the FAA to

acknowledge receipt of their comments

submitted in response to this notice

must submit a self-addressed, stamped

postcard on which the following

statement is made: ‘‘Comments to

Docket Number 94–NM–211–AD.’’ The

postcard will be date stamped and

returned to the commenter.

Availability of NPRMs

Any person may obtain a copy of this

NPRM by submitting a request to the

FAA, Transport Airplane Directorate,

ANM–103, Attention: Rules Docket No.

94–NM–211–AD, 1601 Lind Avenue,

SW., Renton, Washington 98055–4056.

Discussion

On December 9, 1994, the FAA issued

AD 94–26–01, amendment 39–9097 (59

FR 64844, December 16, 1994),

applicable to certain Learjet Model 24,

25, 31, 35, 36, and 55 series airplanes,

and Learjet Model 28 and 29 airplanes,

to require a revision to the Limitations

Section of the FAA-approved Airplane

Flight Manual (AFM) to prohibit flight

above an altitude of 41,000 feet. That

action was prompted originally by a

report of failure of a safety valve in the

pressurization system on a Learjet

Model 31A airplane. Failure of the valve

resulted in depressurization of the

cabin. Investigation revealed that the

poppets of certain outflow/safety valves

were cracked. These discrepant valves,

including the safety valve installed on

the incident airplane, had been

manufactured since January 1, 1989.

Certain valves manufactured since that

date have been found to be susceptible

to cracking due to an improper molding

process. Cracking in the poppets of the

outflow/safety valves in the

pressurization system can result in an

open valve with an effective flow area

of 4.4 square inches; additionally, the

valve may close and remain closed. The

requirements of that AD are intended to

prevent such cracking and subsequent

failure of the valves, which could result

in rapid decompression of the airplane.

When AD 94–26–01 was issued, it

contained a provision for optional

replacement of certain outflow/safety

valves. Accomplishment of the

replacement constitutes terminating

action for the AFM revision; after the

replacement has been accomplished, the

previously required AFM limitation

may be removed. In the preamble to AD

94–26–01, the FAA indicated that it

intended to revise that AD to require the

replacement of those outflow/safety

valves. This action proposes such a

requirement.

The FAA previously reviewed and

approved Allied Signal Aerospace Alert

Service Bulletins 130406–21–A4011,

Revision 2, dated September 28, 1994

(for part number 130406–1); and

102850–21–A4021, Revision 2, dated

October 6, 1994 (for part number

102850–5). These alert service bulletins

describe procedures for replacement of

certain outflow/safety valves in the
14232 Federal Register / Vol. 60, No. 51 / Thursday, March 16, 1995 / Proposed Rules

pressurization system with serviceable

valves. Further, the alert service

bulletins recommend that the maximum

altitude for operation of airplanes that

may be equipped with these outflow/

safety valves be limited to 41,000 feet as

an interim measure until the affected

valves are replaced.

Since the issuance of AD 94–26–01,

Allied Signal Aerospace has issued

Revision 3 of one of the alert service

bulletins described above, Alert Service

Bulletin 130406–21–A4011, dated

January 5, 1995 (for part number

130406–1). The FAA has reviewed and

approved the revised alert service

bulletin, which adds certain valve serial

numbers to the effectivity list of the

alert service bulletin. The FAA has

determined that these additional valve

serial numbers also are subject to the

unsafe condition specified in this AD,

and has referenced Revision 3 of the

alert service bulletin as the appropriate

source of service information for

replacement of outflow/safety valves

having part number 130406–1.

The FAA also has reviewed and

approved the following Learjet service

bulletins, which reference the Allied

Signal Aerospace alert service bulletins

described previously as the appropriate

sources of service information:

1. SB 24/25–21–4, dated January 3,

1995 (for Model 24 and 25 series

airplanes);

2. SB 28/29–21–8, dated January 3,

1995 (for Model 28 and 29 airplanes);

3. SB 31–21–6, dated January 3, 1995

(for Model 31 series airplanes);

4. SB 35/36–21–19, dated January 3,

1995 (for Model 35 and 36 series

airplanes); and

5. SB 55–21–10, dated January 3, 1995

(for Model 55 series airplanes).

Since an unsafe condition has been

identified that is likely to exist or

develop on other products of this same

type design, the proposed AD would

supersede AD 94–26–01 to continue to

require a revision to the Limitations

Section of the FAA-approved Airplane

Flight Manual (AFM) to prohibit flight

above an altitude of 41,000 feet. This

AD also would require replacement of

certain outflow/safety valves.

Accomplishment of the replacement

constitutes terminating action for the

AFM revision; after the replacement has

been accomplished, the previously

required AFM limitation may be

removed. The replacement would be

required to be accomplished in

accordance with the applicable alert

service bulletin described previously.

As a result of recent communications

with the Air Transport Association

(ATA) of America, the FAA has learned

that, in general, some operators may

misunderstand the legal effect of AD’s

on airplanes that are identified in the

applicability provision of the AD, but

that have been altered or repaired in the

area addressed by the AD. The FAA

points out that all airplanes identified in

the applicability provision of an AD are

legally subject to the AD. If an airplane

has been altered or repaired in the

affected area in such a way as to affect

compliance with the AD, the owner or

operator is required to obtain FAA

approval for an alternative method of

compliance with the AD, in accordance

with the paragraph of each AD that

provides for such approvals. A note has

been included in this notice to clarify

this long-standing requirement.

There are approximately 350 Model

24, 25, 31, 35, 36, and 55 series

airplanes and Model 28 and 29

airplanes of the affected design in the

worldwide fleet. The FAA estimates that

280 airplanes of U.S. registry would be

affected by this proposed AD.

The AFM revision required currently

by AD 94–26–01 takes approximately 1

work hour per airplane to accomplish,

at an average labor rate of $60 per work

hour. Based on these figures, the total

cost impact associated with the current

AFM revision requirement of AD 94–

26–01 on U.S. operators is estimated to

be $16,800, or $60 per airplane.

Removal and replacement of parts

that would be required by this proposed

AD would require approximately 12

work hours to accomplish, at an average

labor rate of $60 per work hour.

However, Allied Signal advises that it

will reimburse operators for the costs of

such removal and replacement.

Therefore, based on this information,

U.S. operators would incur no cost

impact for the proposed removal and

replacement requirements.

Based on the figures discussed above,

the (combined) total cost impact of this

AD on U.S. operators would be

approximately $16,800, or $60 per

airplane.

The total cost impact figure discussed

above is based on assumptions that no

operator has yet accomplished any of

the proposed requirements of this AD

action, and that no operator would

accomplish those actions in the future if

this AD were not adopted.

The regulations proposed herein

would not have substantial direct effects

on the States, on the relationship

between the national government and

the States, or on the distribution of

power and responsibilities among the

various levels of government. Therefore,

in accordance with Executive Order

12612, it is determined that this

proposal would not have sufficient

federalism implications to warrant the

preparation of a Federalism Assessment.

For the reasons discussed above, I

certify that this proposed regulation (1)

is not a ‘‘significant regulatory action’’

under Executive Order 12866; (2) is not

a ‘‘significant rule’’ under the DOT

Regulatory Policies and Procedures (44

FR 11034, February 26, 1979); and (3) if

promulgated, will not have a significant

economic impact, positive or negative,

on a substantial number of small entities

under the criteria of the Regulatory

Flexibility Act. A copy of the draft

regulatory evaluation prepared for this

action is contained in the Rules Docket.

A copy of it may be obtained by

contacting the Rules Docket at the

location provided under the caption

ADDRESSES.

List of Subjects in 14 CFR Part 39

Air transportation, Aircraft, Aviation

safety, Safety.

The Proposed Amendment

Accordingly, pursuant to the

authority delegated to me by the

Administrator, the Federal Aviation

Administration proposes to amend 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. App. 1354(a), 1421

and 1423; 49 U.S.C. 106(g); and 14 CFR

11.89.

§ 39.13 [Amended]

2. Section 39.13 is amended by

removing amendment 39–9097 (59 FR

64844, December 16, 1994), and by

adding a new airworthiness directive

(AD), to read as follows:

Learjet: Docket 94–NM–211–AD. Supersedes

AD 94–26–01, Amendment 39–9097.

Applicability: Model 24, 25, 31, 35, 36, and

55 series airplanes, and Model 28 and 29

airplanes; equipped with Allied Signal

outflow/safety valves, number 130406–1 or

102850–5; as identified in Allied Signal

Aerospace Alert Service Bulletin 130406–21–

A4011, Revision 3, dated January 5, 1995; or

102850–21–A4021, Revision 2, dated October

6, 1994; 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

owner/operator must use the authority

provided in paragraph (d) to request approval

from the FAA. This approval may address

either no action, if the current configuration
Federal Register / Vol. 60, No. 51 / Thursday, March 16, 1995 / Proposed Rules 14233

eliminates the unsafe condition; or different

actions necessary to address the unsafe

condition described in this AD. Such a

request should include an assessment of the

effect of the changed configuration on the

unsafe condition addressed by this AD. In no

case does the presence of any modification,

alteration, or repair remove any airplane from

the applicability of this AD.

Compliance: Required as indicated, unless

accomplished previously.

To prevent rapid decompression of the

airplane due to cracking and subsequent

failure of certain outflow/safety valves,

accomplish the following:

(a) Within 30 days after January 3, 1995

(the effective date of AD 94–26–01,

amendment 39–9097), revise the Limitations

Section of the FAA-approved Airplane Flight

Manual (AFM) to include the following. This

may be accomplished by inserting a copy of

this AD in the AFM.

‘‘Operation of the airplane at any altitude

above 41,000 feet is prohibited.’’

(b) Within 18 months after the effective

date of this AD, replace the outflow/safety

valves, part numbers 130406–1 and 102850–

5, as identified in Allied Signal Aerospace

Alert Service Bulletin 130406–21–A4011,

Revision 3, dated January 5, 1995, or 102850–

21–A4021, Revision 2, dated October 6, 1994,

as applicable; with serviceable parts in

accordance with the procedures described in

the applicable alert service bulletin.

Accomplishment of this replacement

constitutes terminating action for the

requirement of paragraph (a) of this AD; after

the replacement has been accomplished, the

previously required AFM limitation may be

removed.

(c) As of January 3, 1995 (the effective date

of AD 94–26–01, amendment 39–9097), no

person shall install an outflow/safety valve,

part number 130406–1 or 102850–5, as

identified in Allied Signal Aerospace Alert

Service Bulletin 130406–21–A4011, Revision

3, dated January 5, 1995, or 102850–21–

A4021, Revision 2, dated October 6, 1994, as

applicable; on any airplane unless that valve

is considered to be serviceable in accordance

with the specifications contained in the

Accomplishment Instructions of the

applicable alert service bulletin.

(d) 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 Aircraft Certification Office (ACO),

FAA, Transport Airplane Directorate.

Operators shall submit their requests through

an appropriate FAA Principal Maintenance

Inspector, who may add comments and then

send it to the Manager, Los Angeles ACO.

Note 2: Information concerning the

existence of approved alternative methods of

compliance with this AD, if any, may be

obtained from the Los Angeles ACO.

(e) 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.

Issued in Renton, Washington, on March 9,

1995.

Neil D. Schalekamp,

Acting Manager, Transport Airplane

Directorate, Aircraft Certification Service.

[FR Doc. 95–6322 Filed 3–15–95; 8:45 am]

BILLING CODE 4910–13–U

14 CFR Part 39

[Docket No. 95–NM–15–AD]

Airworthiness Directives; Boeing

Model B–17E, F, and G Airplanes

AGENCY: Federal Aviation

Administration, DOT.

ACTION: Notice of proposed rulemaking

(NPRM).

SUMMARY: This document proposes the

adoption of a new airworthiness

directive (AD) that is applicable to all

Boeing Model B–17E, F, and G

airplanes. This proposal would require

inspections to detect cracking and

corrosion of the wing spar chords, bolts

and bolt holes of the spar chords, and

wing terminals; and correction of any

discrepancy found during these

inspections. This proposal is prompted

by reports of cracking and corrosion of

the wing spar. The actions specified by

the proposed AD are intended to

prevent reduced structural integrity of

the wing of the airplane due to the

problems associated with corrosion and

cracking of the wing spar.

DATES: Comments must be received by

April 18, 1995.

ADDRESSES: Submit comments in

triplicate to the Federal Aviation

Administration (FAA), Transport

Airplane Directorate, ANM–103,

Attention: Rules Docket No. 95–NM–

15–AD, 1601 Lind Avenue, SW.,

Renton, Washington 98055–4056.

Comments may be inspected at this

location between 9:00 a.m. and 3:00

p.m., Monday through Friday, except

Federal holidays.

FOR FURTHER INFORMATION CONTACT:

Philip Forde, Aerospace Engineer,

Airframe Branch, ANM–120S, FAA,

Transport Airplane Directorate, Seattle

Aircraft Certification Office, 1601 Lind

Avenue, SW., Renton, Washington

98055–4056; telephone (206) 227–2771;

fax (206) 227–1181.

SUPPLEMENTARY INFORMATION:

Comments Invited

Interested persons are invited to

participate in the making of the

proposed rule by submitting such

written data, views, or arguments as

they may desire. Communications shall

identify the Rules Docket number and

be submitted in triplicate to the address

specified above. All communications

received on or before the closing date

for comments, specified above, will be

considered before taking action on the

proposed rule. The proposals contained

in this notice may be changed in light

of the comments received.

Comments are specifically invited on

the overall regulatory, economic,

environmental, and energy aspects of

the proposed rule. All comments

submitted will be available, both before

and after the closing date for comments,

in the Rules Docket for examination by

interested persons. A report

summarizing each FAA-public contact

concerned with the substance of this

proposal will be filed in the Rules

Docket.

Commenters wishing the FAA to

acknowledge receipt of their comments

submitted in response to this notice

must submit a self-addressed, stamped

postcard on which the following

statement is made: ‘‘Comments to

Docket Number 95–NM–15–AD.’’ The

postcard will be date stamped and

returned to the commenter.

Availability of NPRMs

Any person may obtain a copy of this

NPRM by submitting a request to the

FAA, Transport Airplane Directorate,

ANM–103, Attention: Rules Docket No.

95–NM–15–AD, 1601 Lind Avenue,

SW., Renton, Washington 98055–4056.

Discussion

Recently, during routine inspections

of several Boeing Model B–17 series

airplanes, extensive corrosion and

numerous cracks were found on the

tubular spar chords of the inner wing.

These tubular spar chords mate with the

circular inner wing attach fitting inserts

that are held together by close tolerance

bolts. (There are four such joints on

each wing of the airplane.) Investigation

revealed that moisture trapped in the

inner wing spars caused some of the

bolts in the joint assemblies to seize and

corrode. The FAA has determined that

the wing spar assembly is susceptible to

moisture accumulation, which may

result in internal corrosion and

subsequent cracking in this area. Since

this area is subject to maximum bending

and stress loads, cracking in this area is

particularly critical.

This condition, if not corrected and

detected in a timely manner, could

result in reduced structural integrity of

the wing of the airplane.

Since an unsafe condition has been

identified that is likely to exist or

develop on other products of this same

type design, the proposed AD would

require a dye penetrant inspection to