Federal Register / Vol. 62, No. 29 / Wednesday, February 12, 1997 / Rules and Regulations 6459

14 CFR Part 39

[Docket No. 95–NM–02–AD; Amendment

39–9915; AD 97–03–09]

RIN 2120–AA64

Airworthiness Directives; Fokker

Model F28 Mark 0100 Series Airplanes

AGENCY: Federal Aviation

Administration, DOT.

ACTION: Final rule.

SUMMARY: This amendment adopts a

new airworthiness directive (AD),

applicable to certain Fokker Model F28

Mark 0100 series airplanes, that requires

repetitive checks to detect backlash in

the elevator mechanical control system,

and various follow-on actions. This

amendment also provides for an

optional terminating action for the

repetitive check requirements. This

amendment is prompted by a report

indicating that corrosion was found on

the pivot bolts and bushings of the

backlash remover lever mechanism on

the elevator booster control unit (BCU)

of a Model F28 Mark 0100 series

airplane. The actions specified by this

AD are intended to prevent such

corrosion, which could result in

backlash in the elevator controls and

reduced elevator control authority in the

manual mode.

DATES: Effective March 19, 1997.

The incorporation by reference of

certain publications listed in the

regulations is approved by the Director

of the Federal Register as of March 19,

1997.

ADDRESSES: The service information

referenced in this AD may be obtained

from Fokker Aircraft USA, Inc., 1199

North Fairfax Street, Alexandria,

Virginia 22314. 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 Office of the

Federal Register, 800 North Capitol

Street, NW., Suite 700, Washington, DC.

FOR FURTHER INFORMATION CONTACT:

Tim Dulin, Aerospace Engineer,

Standardization Branch, ANM–113,

FAA, Transport Airplane Directorate,

1601 Lind Avenue, SW., Renton,

Washington 98055–4056; telephone

(206) 227–2141; fax (206) 227–1149.

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 Fokker

Model F28 Mark 0100 series airplanes

was published in the Federal Register

on March 17, 1995 (60 FR 14395). That

action proposed to require repetitive

checks to detect backlash in the elevator

mechanical control system, and various

follow-on actions. That action also

proposed an optional terminating action

for the repetitive check requirements.

Interested persons have been afforded

an opportunity to participate in the

making of this amendment. Due

consideration has been given to the

comments received.

Request To Defer Release of Final Rule

One commenter requests that the FAA

defer the release of the final rule until

a bolt replacement program can be

developed to satisfactorily address the

problems with corrosion. This

commenter asserts that the proposed

rule goes beyond what is needed to

address the stated safety concern.

Further, this commenter considers that,

since both U.S. operators affected by

this proposed rule already have

instituted a maintenance program that

includes applying corrosion inhibitor to

the subject bolts, the FAA’s interim

safety objectives are being met. The

commenter also notes that a similar

problem of bolt corrosion occurred on

the same system on a Fokker Model F28

series airplane, and the manufacturer

simply recommended that a corrosionresistant bolt be installed. The

commenter maintains that, if the

proposed rule is adopted without

change, then the FAA will be mandating

a very complex inspection program at

operators’ ‘‘B’’-check intervals, with

little thought to actually correcting the

unsafe condition. If there is a simple,

cost-effective terminating action that

could be introduced—other than the

replacement of the elevator booster

control unit (BCU) with an improved

unit—then it should be considered prior

to going forward with this AD.

The FAA does not concur with the

commenter’s request to delay the

issuance of this AD until a ‘‘bolt

replacement program’’ is developed,

because such a ‘‘program’’ is already

included in the AD as an optional

terminating action. This AD provides for

two optional actions, either of which

could be accomplished in order to

terminate the required repetitive

inspections:

1. modification of the affected BCU by

replacing the currently installed bolts

with improved bolts that are corrosionresistant; or

2. replacement of the currently

installed BCU with a unit that already

has the improved, corrosion-resistant

bolts installed.

The FAA has provided the

terminating actions as optional to

operators, since the accomplishment of

either terminating action is far more

complicated and time-consuming than

performing the required repetitive

operational checks and inspections. For

example, because it is physically

impossible to replace one of the affected

bolts while the BCU is still installed on

the airplane, in order to perform either

terminating action, the BCU must be

removed; this procedure in itself is more

labor-intensive that performing the

required checks and inspections.

However, the FAA maintains that the

accomplishment of either action

provided for in this AD—repetitive

checks/inspections or terminating

action—will adequately address the

unsafe condition presented by

corrosion.

The FAA cannot concur with the

commenter’s suggestion that the FAA’s

‘‘interim safety objectives are being

met’’ by operators’ current practice of

applying a corrosion inhibitor to the

suspect bolts. The commenter provided

no data to substantiate that the

procedure will provide a level of safety

equivalent to that provided by the

actions required by this AD. However,

under the provisions of paragraph (e) of

the final rule, the FAA may approve

requests for use of alternative methods

of compliance if data are submitted to

substantiate that such a method would

provide an acceptable level of safety.

Request To Add ‘‘Intermediate’’ Step in

Operational Check

One commenter requests that the

proposal be revised to include the

‘‘intermediate’’ step of checking the

position of the backlash remover lever,

which is specified in the referenced

Fokker Service Bulletin SBF100–27–

052. This commenter notes that

proposed paragraph (b), as written,

would require an inspection of the

elevator BCU backlash remover bolts for

freedom of movement and corrosion if

any backlash is detected during the

operational check required by proposed

paragraph (a). However, the referenced

Fokker service bulletin specifies an

intermediate step to inspect the position

of the backlash remover to determine

whether the bolt inspection is even

necessary, or if troubleshooting for some

other cause of the problem is necessary.

The FAA concurs with the

commenter’s request. While this

‘‘intermediate’’ step was not specified in

the proposal, the FAA’s intent was to

require operators to accomplish all of

the check and inspection procedures

specified in Fokker Service Bulletin

SBF100–27–052. The final rule has been

revised to indicate that operators are to

perform this intermediate step to

determine if the bolt inspection is
6460 Federal Register / Vol. 62, No. 29 / Wednesday, February 12, 1997 / Rules and Regulations

necessary, rather than immediately

performing the bolt inspection in all

cases. Since this addition to the final

rule is relieving in nature (i.e., operators

may not have to accomplish a more

complicated inspection immediately, as

was proposed), it will not increase the

economic burden on any operator, nor

will it increase the scope of the AD.

Request To Allow Deferment of BCU

Replacement Requirement

One commenter requests that the

proposal be revised to include the

option to defer the replacement of the

elevator BCU prior to further flight if the

backlash remover bolts are found to be

frozen or corroded. The commenter

states that the backlash remover bolts

are neither torqued nor subjected to

high shear loads; therefore, operators

should not be required to remove the

BCU prior to further flight, provided

that the bolts can be freed and

lubricated, and the backlash operational

check is subsequently accomplished

successfully. If removal and

modification of the BCU (in accordance

with Fokker Service Bulletin SBF100–

27–061) could be deferred so that

operators could schedule it during a

regular maintenance interval, the

amount of downtime and additional

expenses could be minimized.

The FAA concurs with the

commenter’s request. If the bolt having

part number NAS6204C22D can be freed

so that it rotates and slides freely, and

is lubricated; and if the backlash

operational check is subsequently

accomplished and is successful; then

the FAA agrees that the replacement of

the elevator BCU can be deferred

somewhat. The FAA considers an

appropriate deferral interval to be 10

days. Paragraph (b) of the final rule has

been revised to specify this deferral

provision.

However, for the bolt having part

number NAS6204C13D, the FAA has

determined that its replacement cannot

be deferred if it does not rotate and slide

freely, or if there are any signs of

corrosion; under those conditions, that

bolt must be replaced prior to further

flight. The FAA considers this action

both appropriate and warranted, since

that bolt is readily accessible on the

airplane.

Request To Add Optional Repetitive

Inspections

One commenter requests that the

proposal be revised to include the

option to conduct periodic inspections

of the backlash remover mechanism and

to apply corrosion preventative

lubrication on the subject backlash

remover bolts at 1,800-flight cycle

intervals. The commenter requests that

operators be permitted to accomplish

these actions in lieu of the proposed

operational checks to detect backlash.

This commenter does not consider the

proposed backlash check from the flight

deck to be a good solution to the

problem of corroded or frozen backlash

remover lever bolts because:

1. the check is subjective, since it

requires a sense of feel that may vary

from person to person; and

2. the check procedures are ill-defined

in the referenced Fokker Service

Bulletin SBF100–27–052.

In addition, this commenter states

that the Fokker service bulletin does not

provide any instructions that will

prevent the existing bolts from

corroding.

This commenter, a U.S. operator,

indicates that it already has

implemented a program that includes

periodic inspection and lubrication of

the subject bolts at 1,800-flight cycle

intervals; the commenter considers its

program to be a more proactive

approach to addressing the unsafe

condition.

The FAA does not concur with the

commenter’s request. In consultation

with Fokker and the Netherlands

airworthiness authority (RLD), the FAA

has determined that the operational

check is not ‘‘subjective,’’ as suggested

by the commenter: there will be a clear

indication of backlash if the mechanism

is stuck, and the referenced Fokker

service bulletin provides objective

standards of approximately 2 inches of

freeplay. In addition, the commenter has

not provided any technical data to prove

that inspection and lubrication of the

bolts at 1,800-flight cycle intervals will

provide at least the same level of safety

as that provided by the operational

check at 500-flight cycle intervals.

While an inspection and lubrication

may help to prevent sticking of the

mechanism, it may not provide the

necessary safety margins. Paragraph (e)

of the final rule, however, does provide

for the use of alternative methods of

compliance with the AD, provided that

sufficient justification is presented to

the FAA.

Further, the FAA agrees that Fokker

Service Bulletin SBF100–27–052 does

not provide instructions to prevent

corrosion, other than inspection and

lubrication of the bolts whenever

backlash is detected during the

operational check. However, this AD

provides for two optional terminating

actions for the checks: either

modification of the existing BCU by

replacing the currently-installed bolts

with corrosion-resistant bolts (as

described in Fokker Service Bulletin

SBF100–26–061); or by replacement of

the affected elevator BCU with a unit

that already has corrosion-resistant bolts

installed. Such replacement of the bolts

positively addresses the problem of

galvanic corrosion.

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.

Cost Impact

The FAA estimates that 112 Fokker

Model F28 Mark 0100 series airplanes of

U.S. registry will be affected by this AD,

that it will take approximately 1 work

hour per airplane to accomplish the

required actions, and that the average

labor rate is $60 per work hour.

Required parts will be supplied by the

manufacturer at no cost to the operators.

Based on these figures, the cost impact

of the AD on U.S. operators is estimated

to be $6,720, or $60 per airplane.

The cost impact figure discussed

above is based on assumptions that no

operator has yet accomplished any of

the requirements of this AD action, and

that no operator would accomplish

those actions in the future if this AD

were not adopted.

Regulatory Impact

The regulations adopted herein will

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 final rule does

not have sufficient federalism

implications to warrant the preparation

of a Federalism Assessment.

For the reasons discussed above, I

certify that this action (1) is not a

‘‘significant regulatory action’’ under

Executive Order 12866; (2) is not a

‘‘significant rule’’ under DOT

Regulatory Policies and Procedures (44

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

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 final evaluation has

been prepared for this action and it is

contained in the Rules Docket. A copy

of it may be obtained from the Rules
Federal Register / Vol. 62, No. 29 / Wednesday, February 12, 1997 / Rules and Regulations 6461

Docket at the location provided under

the caption ADDRESSES.

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:

97–03–09 FOKKER: Amendment 39–9915.

Docket 95–NM–02–AD.

Applicability: Model F28 Mark 0100 series

airplanes; equipped with Menasco Aerospace

Elevator Booster Control Unit (BCU) having

part number (P/N) 23400–3 or P/N 23400–5

with serial numbers MC–001 through MC–

288 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

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

the effect of the modification, alteration, or

repair on the unsafe condition addressed by

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 prevent backlash in the elevator

controls and reduced elevator control

authority in the manual mode, accomplish

the following:

(a) Within 500 flight cycles or 60 days after

the effective date of this AD, whichever

occurs first, perform an operational check to

detect backlash in the elevator mechanical

control system, in accordance with Part 1 of

the Accomplishment Instructions of Fokker

Service Bulletin SBF100–27–052, Revision 1,

dated March 29, 1994. If no backlash is

detected, repeat the check thereafter at

intervals not to exceed 500 flight cycles or 60

days, whichever occurs first.

(b) If any backlash of the elevator

mechanical control system is detected during

any operational check required by paragraph

(a) of this AD, prior to further flight, perform

an inspection to determine whether the

backlash remover lever and pistons are in the

proper position, in accordance with Part 2

(paragraph I.) of Fokker Service Bulletin

SBF100–27–052, Revision 1, dated March 29,

1994.

(1) If the backlash remover lever and

pistons are in the proper position: Prior to

further flight, perform appropriate troubleshooting procedures in accordance with the

Airplane Maintenance Manual.

(2) If the backlash remover lever and

pistons are not in the proper position: Prior

to further flight, perform an inspection to

determine whether the elevator booster

control unit (BCU) bolts, having part

numbers (P/N) NAS6204C22D and P/N

NAS6204C13D, rotate and slide freely; and to

detect corrosion on the bolts of the backlash

remover lever mechanism; in accordance

with Part 2 (paragraph J.) of the

Accomplishment Instructions of Fokker

Service Bulletin SBF100–27–052, Revision 1,

dated March 29, 1994.

(i) If no anomaly is detected, prior to

further flight, perform appropriate troubleshooting procedures in accordance with the

Airplane Maintenance Manual.

(ii) Except as provided by paragraph

(b)(2)(iii) of this AD, if any anomaly is

detected, prior to further flight, replace the

elevator BCU or bolts, as applicable, with

serviceable parts, in accordance with the

service bulletin.

(iii) If any anomaly is detected,

replacement of the elevator BCU or the bolt

having P/N NAS6204C22D, as applicable,

may be deferred for a period of 10 days,

provided that the three conditions specified

below are met:

(A) The bolt having P/N NAS6204C22D

can be freed so that it rotates and slides

freely; and

(B) That bolt is lubricated subsequent to

the inspection; and

(C) An operational check, as specified in

paragraph (a) of this AD, is accomplished

subsequent to lubrication and is successful.

Note 2: The deferral provision of paragraph

(b)(2)(iii) of this AD does not apply to the

bolt having P/N NAS6204C13D. Replacement

of that part-numbered bolt, when necessary,

cannot be deferred.

(c) Terminating action for the repetitive

check and inspection requirements of this

AD consists of the accomplishment of the

actions specified in either paragraph (c)(1) or

(c)(2) of this AD:

(1) Modification of the affected elevator

BCU having P/N 23400–3 or –5, in

accordance with Fokker Service Bulletin

SBF100–27–061, dated March 2, 1994; or

(2) Replacement of any affected elevator

BCU having P/N 23400–3 or –5 with a unit

having a serial number other than MC–001

through MC–288 inclusive, in accordance

with the Airplane Maintenance Manual.

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

person shall install in any airplane a

Menasco Aerospace BCU having P/N 23400–

3 or P/N 23400–5 with serial numbers MC–

001 through MC–288, inclusive.

(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,

Standardization Branch, ANM–113, 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, Standardization

Branch, ANM–113.

Note 3: Information concerning the

existence of approved alternative methods of

compliance with this AD, if any, may be

obtained from the Standardization Branch,

ANM–113.

(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.

(g) The actions shall be done in accordance

with Fokker Service Bulletin SBF100–27–

052, Revision 1, dated March 29, 1994; and

Fokker Service Bulletin SBF100–27–061,

dated March 2, 1994. 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 Fokker Aircraft USA, Inc.,

1199 North Fairfax Street, Alexandria,

Virginia 22314. Copies may be inspected at

the FAA, Transport Airplane Directorate,

1601 Lind Avenue, SW., Renton,

Washington; or at the Office of the Federal

Register, 800 North Capitol Street, NW., Suite

700, Washington, DC.

(h) This amendment becomes effective on

March 19, 1997.

Issued in Renton, Washington, on January

28, 1997.

Darrell M. Pederson,

Acting Manager, Transport Airplane

Directorate, Aircraft Certification Service.

[FR Doc. 97–2608 Filed 2–11–97; 8:45 am]

BILLING CODE 4910–13–U

14 CFR Part 71

[Airspace Docket No. 97–AGL–3]

Modification of Class D Airspace;

Minot, ND

AGENCY: Federal Aviation

Administration (FAA), DOT.

ACTION: Final rule; request for

comments.

SUMMARY: This action modifies Class D

airspace areas at Minot AFB and Minot

International Airport, Minot, ND, by

amending the areas’ effective hours to

coincide with the associated control

tower’s hours of operation. The

intended effect of this action is to clarify

when two-way radio communication

with these air traffic control towers is

required.

DATES: Effective date. 0901 UTC, March

27, 1997.

Comment date. Comments must be

received on or before February 27, 1997.

ADDRESSES: Send comments on the rule

in triplicate to: Manager, Air Traffic