AD 98-26-17

This amendment adopts a new airworthiness directive (AD) that applies to all British Aerospace Jetstream Model 3201 airplanes. This AD requires accomplishing both a routine visual inspection and either a detailed visual inspection or x-ray inspection of the main landing gear (MLG) bay auxiliary spar booms for cracks or fuel leaks on both the left and right sides of the airplane. This AD also requires obtaining and incorporating repair procedures for the MLG bay auxiliary spar where fuel leaks or cracks are found. This AD is the result of mandatory continuing airworthiness information (MCAI) issued by the airworthiness authority for the United Kingdom. The actions specified by this AD are intended to prevent wing failure caused by cracks or fuel leaks in the area of the MLG bay auxiliary spar booms, which could result in loss of control of the airplane.

Final rule

98-26-17 BRITISH AEROSPACE: Amendment 39-10960; Docket No. 98-CE-75-AD.
Applicability: Jetstream Model 3201 airplanes, all serial numbers, 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 in the body of this AD, unless already accomplished.

To prevent wing failure caused by cracks or fuel leaks in the area of the main landing gear (MLG) bay auxiliary spar booms, which could result in loss of control of the airplane, accomplish the following:

(a) Within the next 45 calendar days after the effective date of this AD, accomplish the following:

(1) Perform a routine visual inspection of the MLG bay auxiliary spar booms for cracks or fuel leaks on both the left and right sides of the airplane. Accomplish this inspection in accordance with Part 1 of the Accomplishment Instructions section of British Aerospace Jetstream Alert Service Bulletin 57-A-JA 980441, Original Issue: April 28, 1998, Revision No. 1: July 7, 1998.

(2) Perform either a detailed visual inspection or x-ray inspection of the MLG bay auxiliary spar booms for cracks or fuel leaks on both the left and right sides of the airplane. Accomplish this inspection in accordance with Part 2 of the Accomplishment Instructions section of British Aerospace Jetstream Alert Service Bulletin 57-A-JA 980441, Original Issue: April 28, 1998, Revision No. 1: July 7, 1998.

(b) If cracks or leaks are found during any inspection required by paragraphs (a)(1) and (a)(2) of this AD, prior to further flight, accomplish the following:

(1) Obtain repair instructions from the manufacturer through the FAA, Small Airplane Directorate, at the address specified in paragraph (d) of this AD; and

(2) Incorporate these repair instructions.

(c) 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.

(d) An alternative method of compliance or adjustment of the compliance time that provides an equivalent level of safety may be approved by the Manager, Small Airplane Directorate, Aircraft Certification Service, 1201 Walnut, suite 900, Kansas City, Missouri 64106. The request shall be forwarded through an appropriate FAA Maintenance Inspector, who may add comments and then send it to the Manager, Small Airplane Directorate.

NOTE 2: Information concerning the existence of approved alternative methods of compliance with this AD, if any, may be obtained from the Small Airplane Directorate.

(e) Questions or technical information related to British Aerospace Jetstream Alert Service Bulletin 57-A-JA 980441, Original Issue: April 28, 1998, Revision No. 1: July 7, 1998, should be directed to British Aerospace Regional Aircraft, Prestwick International Airport, Ayrshire, KA9 2RW, Scotland; telephone: (01292) 479888; facsimile: (01292) 479703. This service information may be examined at the FAA, Central Region, Office of the Regional Counsel, Room 1558, 601 E. 12th Street, Kansas City, Missouri 64106.

(f) The inspections required by this AD shall be done in accordance with British Aerospace Jetstream Alert ServiceBulletin 57-A-JA 980441, Original Issue: April 28, 1998, Revision No. 1: July 7, 1998. 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 British Aerospace Regional Aircraft, Prestwick International Airport, Ayrshire, KA9 2RW, Scotland. Copies may be inspected at the FAA, Central Region, Office of the Regional Counsel, Room 1558, 601 E. 12th Street, Kansas City, Missouri, or at the Office of the Federal Register, 800 North Capitol Street, NW, suite 700, Washington, DC.

NOTE 3: The subject of this AD is addressed in British AD 001-04-98, dated May 7, 1998.

(g) This amendment becomes effective on February 5, 1999.

Events Leading to the Issuance of This AD
A proposal to amend part 39 of the Federal Aviation Regulations (14 CFR part 39) to include an AD that would apply to all British Aerospace Jetstream Model 3201 airplanes was published in the Federal Register as a notice of proposed rulemaking (NPRM) on October 13, 1998 (63 FR 54635). The NPRM proposed to require accomplishing both a routine visual inspection and either a detailed visual inspection or x-ray inspection of the MLG bay auxiliary spar booms for cracks or fuel leaks on both the left and right sides of the airplane. The NPRM proposed to also require obtaining and incorporating repair procedures for the MLG bay auxiliary spar where fuel leaks or cracks are found. Accomplishment of the proposed actions as specified in the NPRM would be required in accordance with British Aerospace Jetstream Alert Service Bulletin 57-A-JA 980441, ORIGINAL ISSUE: April 28, 1998, REVISION NO. 1: July 7, 1998.

The NPRM was the result of mandatory continuing airworthiness information (MCAI) issued by the airworthiness authority for the United Kingdom.

Interested persons have been afforded an opportunity to participate in the making of this amendment. No comments were received on the proposed rule or the FAA's determination of the cost to the public.

The FAA's Determination
After careful review of all available information related to the subject presented above, the FAA has determined that air safety and the public interest require the adoption of the rule as proposed except for minor editorial corrections. The FAA has determined that these minor corrections will not change the meaning of the AD and will not add any additional burden upon the public than was already proposed.

Compliance Time of This AD
Although the cracks on the MLG bay auxiliary spar booms could occur as a result of repetitive airplane operation, the FAA believes that the residual stresses in the component are originating from a manufacturing fault during the machining/heat treatment stages. The cracks could exist, but not be noticed, after just a few hours of airplane operation. The stress incurred during flight operations or temperature changes could then cause rapid crack growth. In order to assure that even very small cracks in the MLG bay auxiliary spar booms do not go undetected, the FAA is utilizing a compliance based on calendar time.

Cost Impact
The FAA estimates that 124 airplanes in the U.S. registry will be affected by this AD.

Accomplishing the routine visual inspection required in this AD will take approximately 1 workhour per airplane, at an average labor rate of approximately $60 an hour. Based on these figures, the total cost impact of the routine visual inspection on U.S. operators is estimated to be $7,440, or $60 per airplane.

Accomplishing the detailed visual inspection required in this AD will take approximately 16 workhours per airplane, at an average labor rate of $60 per hour. Accomplishing the x-ray inspection required in this AD will take approximately 12 workhours per airplane, at an average labor rate of approximately $60 an hour. Based on these figures, the total cost impact of the detailed inspection on U.S. operators is estimated to be $119,040, or $960 per airplane, and $89,280, or $720 per airplane for the x-ray inspection.

These figures only take into account the costs of inspections and do not take into account the costs for repairing any MLG bay auxiliary spar boom where fuel leaks or cracks are found during the inspections.

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 copy of the final 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, 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 a new airworthiness directive (AD) to read as follows: