Airworthiness Directives; British Aerospace BAe Model ATP Series Airplanes

DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 97-NM-312-AD]

RIN 2120-AA64

Airworthiness Directives; British Aerospace BAe Model ATP Series

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 BAe

Model ATP airplanes. This proposal would require a one-time inspection

to detect corrosion, wear, or damage of the operating mechanism of the

forward door of the main landing gear (MLG); operational inspections to

ensure smooth operation of the MLG operating mechanism; and follow-on

actions. 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 prevent

partial seizure of the forward door of the MLG operating mechanism,

which could result in the inability to lower or retract the MLG.

DATES: Comments must be received by May 6, 1998.

ADDRESSES: Submit comments in triplicate to the Federal Aviation

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

Attention: Rules Docket No. 97-NM-312-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.

FOR FURTHER INFORMATION CONTACT: Norman B. Martenson, Manager,

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-312-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-312-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

[[Page 16714]]

certain British Aerospace BAe Model ATP airplanes. The CAA advises that

an operator made an emergency landing with the left main landing gear

(MLG) jammed in the ``up'' position. Investigation of the incident

revealed that the probable cause was entrapped grit in the operating

mechanism of the MLG, which caused partial seizure of the spring strut

that drives part of the forward door of the MLG operating mechanism.

Grit and other runway debris also could enter the MLG operating

mechanism of other airplanes with this type design. Resistance in the

MLG operating mechanism caused by entrapped grit can cause the door `A'

frame to function out of sequence with the movement of the oleo (a

cylindrical strut with a built-in telescopic shock absorber that damps

or absorbs rectilinear shock). Such partial seizure of the forward door

of the MLG operating mechanism, if not corrected, could result in the

inability to lower or retract the MLG.

Explanation of Relevant Service Information

The manufacturer has issued British Aerospace Service Bulletin ATP-

32-84, Revision 1, dated September 26, 1997, which describes procedures

for a one-time visual inspection to detect corrosion, wear, or damage

of the operating mechanism of the forward door of the MLG; cleaning,

degreasing, and relubricating the door operating mechanism; and

replacement of worn components with new or serviceable parts.

The service bulletin also describes procedures for repetitive

operational inspections to ensure smooth operation of the spring strut

of the forward door of the MLG, and relubrication of the operating

spring and sliding tube of the forward door `A' frame.

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 Sec. 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 service bulletin described previously,

except as discussed below.

Differences Between This AD and Service Bulletin

Operators should note that, unlike the procedures described in

British Aerospace Service Bulletin ATP-32-84, Revision 1, dated

September 26, 1997, which do not specify actions to be taken if

corroded or damaged parts are detected during inspection, this proposed

AD requires repair of corroded or damaged parts, in accordance with a

method approved by the FAA. Additionally, unlike the service bulletin,

which does not specify action to be taken if smooth operation of the

spring strut cannot be achieved, this proposed AD would require

replacement of discrepant parts with new or serviceable parts, prior to

further flight, in accordance with a method approved by the FAA. The

FAA has determined that, in light of the safety implications and

consequences associated with the discrepancies described previously,

these discrepancies must be corrected prior to further flight.

Cost Impact

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

affected by this proposed AD, that it would take approximately 8 work

hours per airplane to accomplish the proposed actions, 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

$4,800, or $480 per airplane.

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]

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-312-AD.

Applicability: BAe Model ATP airplanes, constructor's number

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 request approval for an

alternative method of compliance in accordance with paragraph (d) 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.

[[Page 16715]]

To prevent partial seizure of the forward door of the main

landing gear (MLG) operating mechanism, which could result in the

inability to lower or retract the MLG, accomplish the following:

(a) Within 300 flight hours or within 90 days after the

effective date of this AD, whichever occurs first, perform a one-

time visual inspection to detect corrosion, wear, or damage of the

operating mechanism of the forward door of the MLG; and clean,

degrease, and relubricate the door operating mechanism; in

accordance with British Aerospace Service Bulletin ATP-32-84,

Revision 1, dated September 26, 1997.

(1) If no corrosion, wear, or damage is detected during the

inspection required by paragraph (a) of this AD, no further action

is required by this AD.

(2) If any corrosion, damage, or worn component is detected

during the inspection required by paragraph (a) of this AD,

accomplish the requirements of paragraphs (a)(2)(i) and (a)(2)(ii)

of this AD, as applicable.

(i) If any corrosion or damage is detected, prior to further

flight, repair in accordance with a method approved by the Manager,

International Branch, ANM-116, FAA, Transport Airplane Directorate.

(ii) If any worn component is detected, within 600 flight hours

after performing the inspection required by paragraph (a) of this

AD, replace the component with a new or serviceable part in

accordance with the service bulletin.

(b) Within 300 flight hours after accomplishing the inspection

required by paragraph (a) of this AD, perform an operational

inspection to ensure smooth operation of the spring strut of the

forward door of the MLG, and relubricate the operating spring and

sliding tube of the forward door `A' frame, in accordance with

British Aerospace Service Bulletin ATP-32-84, Revision 1, dated

September 26, 1997.

(1) Repeat the operational inspections thereafter at intervals

not to exceed 300 flight hours, until the accumulation of 1,500

flight hours after the accomplishment of the inspection required by

paragraph (a) of this AD.

(2) Following the accomplishment of all inspections required by

paragraph (b)(1) of this AD, repeat the operational inspections and

relubrication required by paragraph (b) of this AD at intervals not

to exceed 1,500 flight hours.

(c) If any discrepancy is detected during any operational

inspection and relubrication required by paragraph (b) of this AD,

prior to further flight, replace any discrepant part with a new or

serviceable part in accordance with a method approved by the

Manager, International Branch, ANM-116.

(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, 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.

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

Secs. 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 31, 1998.

Darrell M. Pederson,

Acting Manager, Transport Airplane Directorate, Aircraft Certification

Service.

[FR Doc. 98-8901 Filed 4-3-98; 8:45 am]

BILLING CODE 4910-13-U