Airworthiness Directives; Fokker Model F28 Mark 0100 Series Airplanes

DEPARTMENT OF TRANSPORTATION

14 CFR Part 39

[Docket No. 93-NM-197-AD]

Airworthiness Directives; Fokker Model F28 Mark 0100 Series

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 certain Fokker Model F28 Mark 0100

series airplanes. This proposal would require inspections to detect

cracks of certain demountable flange (inboard) wheel subassemblies and

of the bolt bosses on certain demountable flange (outboard) wheel

subassemblies, and modification or replacement, if necessary. This

proposal is prompted by reports of cracks and broken spokes found on

certain main wheel assemblies of these airplanes. The actions specified

by the proposed AD are intended to prevent loss of a main wheel

assembly during takeoff or landing.

DATES: Comments must be received by April 25, 1994.

ADDRESSES: Submit comments in triplicate to the Federal Aviation

Administration (FAA), Transport Airplane Directorate, ANM-103,

Attention: Rules Docket No. 93-NM-197-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 Fokker Aircraft USA, Inc., 1199 North Fairfax Street,

Alexandria, Virginia 22314. This information may be examined at the

FAA, Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton,

Washington.

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) 227-1320.

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 93-NM-197-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. 93-NM-197-AD, 1601 Lind Avenue, SW., Renton, Washington

98055-4056.

Discussion

The Rijksluchtvaartdienst (RLD), which is the airworthiness

authority for the Netherlands, recently notified the FAA that an unsafe

condition may exist on certain Fokker Model F28 Mark 0100 series

airplanes. The RLD advises that several operators of Model F28 Mark

0100 series airplanes have reported finding cracks and broken spokes on

certain main wheel assemblies, part number 5008131-4. Investigation

revealed that the manufacturer of these wheels had discontinued a shot-

peening procedure that was part of the manufacturing process prior to

April 1991. Subsequently, an improved shot-peening procedure on the

mating surfaces of the inboard wheel subassemblies was introduced in

October 1992. However, this procedure was not introduced on the

outboard wheel subassemblies until February 1993. Consequently, a

number of units were produced that are prone to fretting and cracking

due to a lack of shot-peening of the assembly mating surfaces and bolt

bosses. This condition, if not corrected, could result in loss of a

main wheel assembly during takeoff or landing.

Fokker has issued Service Bulletins SBF100-32-070, dated January

18, 1993, and SBF100-32-073, dated September 10, 1993, which reference

Aircraft Braking Systems Corporation (ABSC) Service Bulletins Fo100-32-

46, dated December 24, 1992, and Fo100-32-48, dated March 10, 1993, as

the appropriate sources of service information. The RLD classified

these Fokker service bulletins as mandatory and issued Netherlands

Airworthiness Directive (BLA) 93-009/3 (A), dated June 1, 1993, in

order to assure the continued airworthiness of these airplanes in the

Netherlands.

ABSC Service Bulletin Fo100-32-46 describes procedures for eddy

current inspections to detect cracks of certain demountable flange

(inboard) wheel subassemblies; and, if no cracks are found,

modification and subsequent inspections of the subassemblies; and, if

cracks are found, replacement of the subassemblies with serviceable

parts.

ABSC Service Bulletin Fo100-32-48 describes procedures for eddy

current inspections to detect cracks of the bolt bosses of certain

demountable flange (outboard) wheel subassemblies; and, if no cracks

are found, modification of the subassemblies; and, if cracks are found,

replacement of the subassemblies with serviceable parts.

This airplane model is manufactured in the Netherlands and is type

certificated for operation in the United States under the provisions of

Sec. 21.29 of the Federal Aviation Regulations and the applicable

bilateral airworthiness agreement. Pursuant to this bilateral

airworthiness agreement, the RLD has kept the FAA informed of the

situation described above. The FAA has examined the findings of the

RLD, reviewed all available information, and determined that AD action

is necessary for products of this type design that are certificated for

operation in the United States.

Since an unsafe condition has been identified that is likely to

exist or develop on other airplanes of the same type design registered

in the United States, the proposed AD would require repetitive eddy

current inspections to detect cracks of certain demountable flange

(inboard) wheel subassemblies and of the bolt bosses of certain

demountable flange (outboard) wheel subassemblies, and modification or

replacement, if necessary. Replacement of a cracked wheel subassembly

terminates certain repetitive inspections required by this AD. The

actions would be required to be accomplished in accordance with the

ABSC service bulletins described previously.

The FAA estimates that 87 airplanes of U.S. registry would be

affected by this proposed AD, that it would take approximately 14 work

hours per airplane to accomplish the proposed inspection and

modification, and that the average labor rate is $55 per work hour.

Based on these figures, the total cost impact of the proposed AD on

U.S. operators is estimated to be $66,990, or $770 per airplane. This

total cost figure assumes that no operator has yet accomplished the

proposed requirements of this AD action.

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 14

CFR part 39 of the Federal Aviation Regulations 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 adding the following new

airworthiness directive:

Fokker: Docket 93-NM-197-AD.

Applicability: Model F28 Mark 0100 series airplanes equipped

with Aircraft Braking Systems Corporation (ABSC) main wheel

assembly, part number 5008131-4, serial numbers APR91-0570 through

FEB93-0965 inclusive; certificated in any category.

Compliance: Required as indicated, unless accomplished

previously. To prevent loss of a main wheel assembly during takeoff

or landing, accomplish the following:

(a) For airplanes equipped with a demountable flange (inboard)

wheel subassembly, part number 5008142-4, serial numbers APR91-0570

through OCT92-0858 inclusive, or S-APR91-0097 through S-MAY92-0126

inclusive: Within 100 landings after the effective date of this AD,

or at the next tire change, whichever occurs first, perform an eddy

current inspection to detect cracks of the wheel subassembly, in

accordance with paragraph C. of Section II--Accomplishment

Instructions of ABSC Service Bulletin Fo100-32-46, dated December

24, 1992. Repeat this inspection thereafter at intervals not to

exceed 500 landings or at each tire change, whichever occurs first.

(1) If no crack is found during any inspection required by

paragraph (a) of this AD: Prior to further flight following the

third inspection, modify the wheel subassembly in accordance with

paragraph D. of Section II--Accomplishments Instructions of the

service bulletin. After modification, continue to inspect in

accordance with paragraph (a) of this AD. If no crack is found

during the first two inspections conducted after modification, no

further action is required by this paragraph.

(2) If any crack is found during any inspection required by

paragraph (a) of this AD, prior to further flight, replace the wheel

subassembly, part number 5008142-4, with a serviceable part. Such

replacement constitutes terminating action for the repetitive

inspections required by paragraph (a) of this AD.

(b) For airplanes equipped with a demountable flange (outboard)

wheel subassembly, part number 5008140-1, serial numbers APR91-0570

through FEB93-0965 inclusive, or S-MAR91-0002 through S-FEB93-0010

inclusive: Within 100 landings after the effective date of this AD,

or at the next tire change, whichever occurs first, perform an eddy

current inspection to detect cracks of the bolt bosses of the wheel

subassembly, in accordance with paragraph B. of Section II--

Accomplishment Instructions of ABSC Service Bulletin Fo100-32-48,

dated March 10, 1993. Repeat this inspection thereafter at interals

not to exceed 500 landings or at each tire change, whichever occurs

first.

(1) If no crack is found during any inspection required by

paragraph (b) of this AD: Prior to further flight following the

third inspection, modify the wheel subassembly in accordance with

paragraph C. of Section II--Accomplishment Instructions of the

service bulletin. Such modification constitutes terminating action

for the repetitive inspections required by paragraph (b) of this AD.

(2) If any crack is found during any inspection required by

paragraph (b) of this AD, prior to further flight, replace the wheel

subassembly, part number 5008140-1, with a serviceable part. Such

replacement constitutes terminating action for the repetitive

inspections required by paragraph (b) of this AD.

(c) After the effective date of this AD, no person shall install

any of the following parts on any airplane unless that part has been

inspected and modified in accordance with paragraph (a) and/or (b)

of this AD, as applicable.

(1) ABSC demountable flange (inboard) wheel subassembly, part

number 5008142-4, having serial numbers APR91-0570 through OCT92-

0858 inclusive, or S-APR91-0097 through S-MAY92-0126 inclusive;

(2) ABSC demountable flange (outboard) wheel subassembly, part

number 5008140-1, having serial numbers APR91-0570 through FEB93-

0965 inclusive, or S-MAR91-0002 through S-FEB93-0010 inclusive;

(3) Main wheel assembly, part number 5008131-4, having serial

numbers APR91-0570 through FEB 93-0965 inclusive.

(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, 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: Information concerning the existence of approved

alternative methods of compliance with this AD, if any, may be

obtained from the Standardization Branch, ANM-113.

(e) Special flight permits may be issued in accordance with

Federal Aviation Regulations (FAR) 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 February 22, 1994.

Darrell M. Pederson,

Acting Manager, Transport Airplane Directorate, Aircraft Certification

Service.

[FR Doc. 94-4450 Filed 2-25-94; 8:45 am]

BILLING CODE 4910-13-U