Airworthiness Directives; Jetstream Model ATP Airplanes

DEPARTMENT OF TRANSPORTATION

14 CFR Part 39

[Docket No. 94-NM-173-AD]

Airworthiness Directives; Jetstream Model ATP Airplanes

AGENCY: Federal Aviation Administration, DOT.

ACTION: Notice of proposed rulemaking (NPRM).

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SUMMARY: This document proposes the supersedure of an existing

airworthiness directive (AD), applicable to certain Jetstream Model ATP

airplanes, that currently requires daily and/or pre-

[[Page 30799]] flight cleaning and inspections to detect damaged main

landing gear (MLG) wheel bearings and replacement of discrepant parts.

That AD was prompted by reports of failure of the MLG wheel bearings.

The actions specified by that AD are intended to prevent failure of the

MLG wheel bearing, which could result in detachment of a MLG wheel from

the airplane. This action would require an additional inspection, in

lieu of the pre-flight inspection, for certain airplanes. This action

would also require the accomplishment of a terminating modification

that would eliminate the need for daily and pre-flight inspections.

DATES: Comments must be received by July 24, 1995.

ADDRESSES: Submit comments in triplicate to the Federal Aviation

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

Attention: Rules Docket No. 94-NM-173-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.

The service information referenced in the proposed rule may be

obtained from Jetstream Aircraft, Inc., P.O. Box 16029, Dulles

International Airport, Washington, DC 20041-6029. This information may

be examined at the FAA, Transport Airplane Directorate, 1601 Lind

Avenue, SW., Renton, Washington.

FOR FURTHER INFORMATION CONTACT: William Schroeder, Aerospace Engineer,

Standardization Branch, ANM-113, FAA, Transport Airplane Directorate,

1601 Lind Avenue, SW., Renton, Washington 98055-4056; telephone (206)

227-2148; fax (206) 227-1149.

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-173-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-173-AD, 1601 Lind Avenue, SW., Renton, Washington

98055-4056.

Discussion

On February 18, 1994, the FAA issued AD 94-05-03, amendment 39-8841

(59 FR 9400, February 28, 1994), applicable to certain Jetstream Model

ATP airplanes, to require daily and/or pre-flight cleaning and detailed

visual inspections to detect damage or discoloration of the main wheel

hub caps and of the outer side of each inflation valve side hubs on the

main landing gear (MLG) wheels. That amendment also requires

replacement of the damaged or discolored MLG wheel assembly and

bearings with a serviceable wheel assembly and bearings. That action

was prompted by reports of failure of the MLG wheel bearings. The

requirements of that AD are intended to prevent detachment of a MLG

wheel from the airplane.

Since the issuance of that AD, Jetstream has issued Revision 3 of

Service Bulletin ATP-32-48, dated July 15, 1994. The daily cleaning and

detailed visual inspection, and pre-flight detailed visual inspection

procedures described in this revision are essentially identical to

those described in Revision 1 of the service bulletin (which was

referenced in AD 94-05-03 as the appropriate source of service

information). For certain airplanes Revision 3 of the service bulletin

describes procedures for performing an additional intermediate detailed

visual inspection, in lieu of the pre-flight inspection. This

intermediate inspection would detect damage (including blistering or

flaking of the paint) or heat discoloration of the wheel hub cap and

the outer side of each inflation valve side hub on the MLG wheels.

Jetstream has also issued Service Bulletin ATP-32-51-35296A, dated

May 12, 1994, which describes procedures for modification of the MLG.

This modification involves drilling two additional locking holes in

each axle. This modification will reduce the axial movement between the

locking positions to provide a closer control of the wheel bearing

preload.

Additionally, Jetstream issued Service Bulletin ATP-32-53-35294A

(including Erratum No. 1), dated July 18, 1994, and Revision 2, dated

January 13, 1995, which describe procedures for modification of certain

wheels on the MLG. This modification involves removing the existing

valve side half hub assembly of the wheel and installing a new valve

side half hub assembly, which is capable of accepting a new outer

bearing with higher load capability.

Accomplishment of these modifications described in Service

Bulletins ATP-32-51-35296A and ATP-32-53-35294A would eliminate the

need for the daily, pre-flight, and daily intermediate inspections, and

would positively address the unsafe condition identified as detachment

of a MLG wheel from the airplane.

The Civil Aviation Authority (CAA), which is the airworthiness

authority for the United Kingdom, has classified these service

bulletins as mandatory in order to assure the continued airworthiness

of these airplanes in the United Kingdom.

This airplane model is manufactured in the United Kingdom and is

type certificated for operation in the United States under the

provisions of section 21.29 of the Federal Aviation Regulations (14 CFR

21.29) and the applicable bilateral airworthiness agreement. Pursuant

to this bilateral airworthiness agreement, the CAA has kept the FAA

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

findings of the CAA, 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 supersede AD 94-05-03 to

continue to require daily cleaning and daily/pre-flight detailed visual

inspections to detect damage (including blistering or flaking of the

paint) or discoloration of the wheel hub caps and of the outer side of

the inflation valve side hubs on the MLG wheels. The proposed AD would

[[Page 30800]] also require an additional daily intermediate detailed

visual inspection, in lieu of the pre-flight inspection, for certain

airplanes. This intermediate inspection would detect damage or heat

discoloration of the wheel hub cap and the outer side of each inflation

valve side hub on the MLG wheel. Additionally, the proposed AD would

require modification of the MLG, which would constitute terminating

action for the daily, pre-flight, daily intermediate inspection

requirements. The actions would be required to be accomplished in

accordance with the service bulletins described previously. If any

damage or discoloration is found, the replacement of the existing MLG

wheel assembly and bearings with a serviceable wheel assembly and

bearings would be required to be accomplished in accordance with a

method approved by the FAA.

The FAA estimates that 10 airplanes of U.S. registry would be

affected by this proposed AD.

The inspections that were previously required by AD 94-05-03, and

would be retained in this proposed AD, take approximately 2 work hours

per airplane to accomplish, at an average labor rate of $60 per work

hour. Based on these figures, the total cost impact of the inspection

requirement of this AD on U.S. operators is estimated to be $1,200, or

$120 per airplane, per inspection cycle.

The inspections that would be added by this proposed AD would take

approximately 2 work hours per airplane to accomplish , at an average

labor rate of $60 per work hour. Based on these figures, the total cost

impact of the inspections proposed by this AD on U.S. operators is

estimated to be $1,200, or $120 per airplane, per inspection cycle.

It would take approximately 11 work hours per airplane to

accomplish the proposed modifications at an average labor rate of $60

per work hour. Required parts would be supplied by the manufacturer at

no cost to the operators. Based on these figures, the total cost impact

of the modification proposed by this AD on U.S. operators is estimated

to be $6,600, or $660 per airplane.

The total cost impact figures discussed above are 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.

Sec. 39.13 [Amended]

2. Section 39.13 is amended by removing amendment 39-8841 (59 FR

9400, February 28, 1994), and by adding a new airworthiness directive

(AD), to read as follows:

Jetstream Aircraft Limited (Formerly British Aerospace Commercial

Aircraft Limited): Docket 94-NM-173-AD. Supersedes AD 94-05-03,

Amendment 39-8841.

Applicability: Model ATP airplanes, constructor numbers 2001

through 2063 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 use the authority

provided in paragraph (d) to request approval from the FAA. This

approval may address either no action, if the current configuration

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 detachment of a main landing gear (MLG) wheel from

the airplane, accomplish the following:

(a) For airplanes on which Jetstream Modification 35296A

(reference Jetstream Service Bulletin ATP-32-51-35296A) has not been

installed: Accomplish paragraphs (a)(1) and (a)(2) of this AD.

(1) Within 24 hours after March 15, 1994 (the effective date of

AD 94-05-03, amendment 39-8841), perform a cleaning and a detailed

visual inspection to detect damage (including blistering or flaking

of the paint) or discoloration of the wheel hub caps and of the

outer side of the inflation valve side hubs on the MLG wheels, in

accordance with paragraph 2.(2) of the Accomplishment Instructions

of Jetstream Service Bulletin ATP-32-48, Revision 1, dated January

28, 1994; or in accordance with paragraph 2.A.(2) of the

Accomplishment Instructions of Jetstream Service Bulletin ATP-32-48,

Revision 3, dated July 15, 1994. Thereafter, prior to the first

flight of each day, repeat this cleaning and inspection. The

cleaning and inspection must be performed by appropriately

certificated maintenance personnel as specified in section 43.3 of

the Federal Aviation Regulations (14 CFR 43.3). If any damage or

discoloration is found during any inspection required by this

paragraph, prior to further flight, replace the existing MLG wheel

assembly and bearings with a serviceable wheel assembly and

bearings, in accordance with the airplane maintenance manual.

(2) Following accomplishment of the initial inspection required

by paragraph (a)(1) of this AD, prior to each flight, with the

exception of the first flight of each day, perform a pre-flight

detailed visual inspection to detect damage (including blistering or

flaking of the paint) or heat discoloration of the wheel hub cap and

the outer side of each inflation valve side hub on the MLG wheels,

in accordance with paragraph 2.A.(3) of the Accomplishment

Instructions of Jetstream Service Bulletin ATP-32-48, Revision 1,

dated January 28, 1994; or in accordance with paragraph 2.A.(3) of

the Accomplishment Instruction of Jetstream Service Bulletin ATP-32-

48, Revision 3, dated July 15, 1994. The pre-flight inspections must

be performed by appropriately certificated maintenance personnel, as

specified in section 43.3. If any damage or discoloration is found

during any inspection required by this paragraph, prior to further

flight, replace the existing MLG wheel assembly and bearings with a

[[Page 30801]] serviceable wheel assembly and bearings, in

accordance with the airplane maintenance manual.

(b) For airplanes on which Jetstream Modification 35296A

(reference Jetstream Service Bulletin ATP-32-51-35296A) has been

installed: Accomplish paragraphs (b)(1) and (b)(2) of this AD.

(1) Within 24 hours after the last inspection performed in

accordance with paragraph (a)(1) of this AD, perform a cleaning and

a detailed visual inspection to detect damage (including blistering

or flaking of the paint) or discoloration of the wheel hub caps and

of the outer side of the inflation valve side hubs on the MLG

wheels, in accordance with paragraph 2.Part B.(2) of the

Accomplishment Instructions of Jetstream Service Bulletin ATP-32-48,

Revision 3, dated July 15, 1994. Thereafter, prior to the first

flight of each day, repeat this cleaning and inspection. The

cleaning and inspection must be performed by appropriately

certificated maintenance personnel as specified in section 43.3 of

the Federal Aviation Regulations (14 CFR 43.3). If any damage or

discoloration is found during any inspection required by this

paragraph, prior to further flight, replace the existing MLG wheel

assembly and bearings with a serviceable wheel assembly and

bearings, in accordance with the airplane maintenance manual.

(2) Following accomplishment of the initial inspection required

by paragraph (b)(1) of this AD, once a day, perform an additional

intermediate detailed visual inspection to detect damage (including

blistering or flaking of the paint) or heat discoloration of the

wheel hub cap and the outer side of each inflation valve side hub on

the MLG wheels, in accordance with paragraph 2.Part B.(3) of the

Accomplishment Instructions of Jetstream Service Bulletin ATP-32-48,

Revision 3, dated July 15, 1994. The once-a-day inspections must be

performed by appropriately certificated maintenance personnel, as

specified in 14 CFR 43.3. If any damage or discoloration is found

during any inspection required by this paragraph, prior to further

flight, replace the existing MLG wheel assembly and bearings with a

serviceable wheel assembly and bearings, in accordance with the

airplane maintenance manual.

(c) Within 10 months after the effective date of this AD, modify

the MLG, in accordance with Jetstream Service Bulletin ATP-32-51-

35296A (including Erratum No. 1), dated May 12, 1994; and Jetstream

Service Bulletin ATP-32-53-35294A, dated July 18, 1994, or Revision

2, dated January 13, 1995. Accomplishment of these modifications

constitutes terminating action for the daily and pre-flight

inspection requirements of this AD.

(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 2: 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

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 June 6, 1995.

Darrell M. Pederson,

Acting Manager, Transport Airplane Directorate, Aircraft Certification

Service.

[FR Doc. 95-14316 Filed 6-9-95; 8:45 am]

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