Airworthiness Directives; British Aerospace (Jetstream) Model 4101 Airplanes

DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 97-NM-141-AD]

RIN 2120-AA64

Airworthiness Directives; British Aerospace (Jetstream) Model

4101 Airplanes

AGENCY: Federal Aviation Administration, DOT.

ACTION: Notice of proposed rulemaking (NPRM).

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SUMMARY: This document proposes the adoption of a new airworthiness

directive (AD) that is applicable to certain British Aerospace

(Jetstream) Model 4101 airplanes. This proposal would require

repetitive detailed visual inspections to detect cracking or other

damage of certain diaphragm support structures of the forward equipment

compartment; and repair, if necessary. This proposal is prompted by

issuance of mandatory continuing airworthiness information by a foreign

civil airworthiness authority. The actions specified by the proposed AD

are intended to detect and correct failure of the two diaphragms that

support the upper structure of the forward equipment compartment, which

could accelerate fatigue damage in adjacent structure and result in

reduced structural integrity of the airframe.

DATES: Comments must be received by February 9, 1998.

ADDRESSES: Submit comments in triplicate to the Federal Aviation

Administration (FAA), Transport Airplane Directorate, ANM-114,

Attention: Rules Docket No. 97-NM-141-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 AI(R) American Support, Inc., 13850 Mclearen Road,

Herndon, Virginia 20171. This information may be examined at the FAA,

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

Washington.

ments 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 AI(R) American Support, Inc., 13850 Mclearen Road,

Herndon, Virginia 20171. This information may be examined at the FAA,

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

Washington.

FOR FURTHER INFORMATION CONTACT: International Branch, ANM-116, FAA,

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

Washington 98055-4056; telephone (425) 227-2110; fax (425) 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 97-NM-141-AD.'' The postcard will be date stamped and

returned to the commenter.

Availability of NPRMs

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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 97-NM-141-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-114, Attention: Rules

Docket No. 97-NM-141-AD, 1601 Lind Avenue, SW., Renton, Washington

98055-4056.

Discussion

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

authority for the United Kingdom, notified the FAA that an unsafe

condition may exist on certain British Aerospace (Jetstream) Model 4101

airplanes. The CAA advises that, during fatigue testing, cracks were

found in the two diaphragms that support the upper structure of the

forward equipment compartment. This condition, if not detected and

corrected in a timely manner, could accelerate fatigue damage in

adjacent structure and result in reduced structural integrity of the

airframe.

Explanation of Relevant Service Information

The manufacturer has issued Jetstream Alert Service Bulletin J41-

A53-023, dated December 2, 1996, which describes procedures for

repetitive detailed visual inspections to detect cracking or other

damage of certain diaphragms that support the upper structure of the

forward equipment compartment; and repair, if necessary. The CAA

classified this alert service bulletin as mandatory and issued British

airworthiness directive 007-12-96, in order to assure the continued

airworthiness of these airplanes in the United Kingdom.

FAA's Conclusions

visual inspections to detect cracking or other

damage of certain diaphragms that support the upper structure of the

forward equipment compartment; and repair, if necessary. The CAA

classified this alert service bulletin as mandatory and issued British

airworthiness directive 007-12-96, in order to assure the continued

airworthiness of these airplanes in the United Kingdom.

FAA's Conclusions

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.

Explanation of Requirements of Proposed Rule

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 accomplishment of

the actions specified in the alert service bulletin described

previously, except as discussed below.

Differences Between Proposed Rule and Service Bulletin

Operators should note that, unlike the procedures described in

Jetstream Alert Service Bulletin J41-A53-023, dated December 2, 1996,

this proposed AD would not permit further flight if cracks are detected

in certain diaphragms that support the upper structure of the forward

equipment compartment. The FAA has determined that, because of the

safety implications and consequences associated with such cracking, any

subject diaphragm that is found to be cracked must be repaired or

modified prior to further flight

ember 2, 1996,

this proposed AD would not permit further flight if cracks are detected

in certain diaphragms that support the upper structure of the forward

equipment compartment. The FAA has determined that, because of the

safety implications and consequences associated with such cracking, any

subject diaphragm that is found to be cracked must be repaired or

modified prior to further flight.

Operators should also note that, although the alert service

bulletin specifies that the manufacturer may be contacted for

disposition of certain repair conditions, this proposal would require

the repair of those conditions to be accomplished in accordance with a

method approved by the FAA.

The proposed AD also would differ from the alert service bulletin

in that it would continue to require repetitive inspections after a

repair to cracked or damaged diaphragms is accomplished. The alert

service bulletin considers the accomplishment of the repair as

terminating action for the repetitive inspections. The FAA requires

further evidence that the repair will be effective in preventing

further cracking or damage.

Interim Action

This is considered to be interim action until final action is

identified, at which time the FAA may consider further rulemaking.

Cost Impact

The FAA estimates that 55 airplanes of U.S. registry would be

affected by this proposed AD, that it would take approximately 1 work

hour per airplane to accomplish the proposed inspection, and that the

average labor rate is $60 per work hour. Based on these figures, the

cost impact of the proposed AD on U.S. operators is estimated to be

$3,300, or $60 per airplane, per inspection cycle.

The 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.

Regulatory Impact

res, the

cost impact of the proposed AD on U.S. operators is estimated to be

$3,300, or $60 per airplane, per inspection cycle.

The 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.

Regulatory Impact

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. 106(g), 40113, 44701.

Sec. 39.13 [Amended]

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. 106(g), 40113, 44701.

Sec. 39.13 [Amended]

2. Section 39.13 is amended by adding the following new

airworthiness directive:

British Aerospace Regional Aircraft [Formerly Jetstream Aircraft

Limited; British Aerospace (Commercial Aircraft) Limited]: Docket

97-NM-141-AD.

Applicability: Jetstream Model 4101 airplanes, constructors

numbers 41004 through 41098 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 (b) 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 detect and correct failure of the two diaphragms that support

the upper structure of the forward equipment compartment, which

could accelerate fatigue damage in adjacent structure and result in

reduced structural integrity of the airframe, accomplish the

following:

should include specific proposed actions to

address it.

Compliance: Required as indicated, unless accomplished

previously.

To detect and correct failure of the two diaphragms that support

the upper structure of the forward equipment compartment, which

could accelerate fatigue damage in adjacent structure and result in

reduced structural integrity of the airframe, accomplish the

following:

(a) Prior to the accumulation of 4,500 total landings, or within

300 landings after the effective date of this AD, whichever occurs

later: Perform a detailed visual inspection to detect cracking or

other damage of the diaphragms installed between station 4 and

station 8 of the forward fuselage, in accordance with Jetstream

Alert Service Bulletin J41-A53-023, dated December 2, 1996.

(1) If no cracking or other damage is detected, repeat the

inspection thereafter at intervals not to exceed 3,000 landings.

(2) If any cracking or other damage is detected, prior to

further flight, repair the diaphragm in accordance with a method

approved by the Manager, International Branch, ANM-116, FAA,

Transport Airplane Directorate. Thereafter, repeat the inspection at

intervals not to exceed 3,000 landings.

(b) 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, International Branch, ANM-116.

Operators shall submit their requests through an appropriate FAA

Principal Maintenance Inspector, who may add comments and then send

it to the Manager, International Branch, ANM-116.

Note 2: Information concerning the existence of approved

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

obtained from the International Branch, ANM-116.