AD 96-22-02

This amendment adopts a new airworthiness directive (AD), applicable to certain Jetstream Model BAe ATP airplanes, that requires repetitive inspections of the ram air inlet ducts for structural integrity and security of fasteners, and repairs, if necessary. This amendment also provides an optional terminating modification for the repetitive inspections. This amendment is prompted by a report of the separation of a ram air inlet duct from the airplane during flight. The actions specified by this AD are intended to prevent such separation, which could pose a hazard to persons or property on the ground.

Final rule

96-22-02 JETSTREAM AIRCRAFT, LTD. (Formerly British Aerospace Commercial Aircraft, Limited): Amendment 39-9791. Docket 96-NM-139-AD.
Applicability: Model BAe ATP airplanes having constructor numbers 2002 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 otherwise 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 (c) 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 actionsto address it.

Compliance: Required as indicated, unless accomplished previously.

To prevent the separation of the ram air inlet duct from the airplane, accomplish the following:

(a) Prior to the accumulation of 50 flight hours after the effective date of this AD, inspect the left and right ram air inlet ducts to determine whether the duct base plate flange has delaminated and the screws fastening the duct have pulled through the duct base plate, in accordance with Jetstream BAe ATP Service Bulletin ATP-21-36, dated January 3, 1996.

(1) If no discrepancy is detected, repeat the inspection thereafter at intervals not to exceed 250 flight hours.

(2) If any discrepancy is detected, prior to further flight, repair in accordance with the service bulletin. Thereafter, repeat the inspection at intervals not to exceed 250 flight hours.

(b) Accomplishment of the modification of the ram air inlet ducts in accordance with Jetstream BAe ATP Service Bulletin ATP-21-37, dated January 23, 1996, constitutes terminating action for the repetitive inspections required by paragraph (a) of this AD.

(c) 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.

(d) 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.

(e) The inspections and repair shall be done in accordance with Jetstream BAe ATP Service Bulletin ATP-21-36, dated January 3, 1996. 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 Jetstream Aircraft, Inc., P.O. Box 16029, Dulles International Airport, Washington, DC 20041-6029. Copies may be inspected at the FAA, Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton, Washington; or at the Office of the Federal Register, 800 North Capitol Street, NW., suite 700, Washington, DC.

(f) This amendment becomes effective on December 11, 1996.

A proposal to amend part 39 of the Federal Aviation Regulations (14 CFR part 39) to include an airworthiness directive (AD) that is applicable to certain Jetstream Model BAe ATP airplanes was published in the Federal Register on August 12, 1996 (61 FR 41757). That action proposed to require the inspection of the airplane s left and right ram air inlet ducts to determine whether the duct base plate flange has delaminated and the screws fastening these ducts have pulled through the duct base plate; and would require repair, if necessary. The action also proposed to require repetitive inspections and repairs, if necessary, unless an optional terminating action is performed.

Interested persons have been afforded an opportunity to participate in the making of this amendment. No comments were submitted in response to the proposal or the FAA's determination of the cost to the public.

Conclusion
The FAA has determined that air safety and the public interest require the adoption of the rule as proposed.

Cost Impact
The FAA estimates that 10 Jetstream Model BAe ATP airplanes of U.S. registry will be affected by this AD, that it will take approximately 1 work hour per airplane to accomplish the required actions, and that the average labor rate is $60 per work hour. Based on these figures, the cost impact of the AD on U.S. operators is estimated to be $600 per inspection, or $60 per airplane, per inspection.

The cost impact figure discussed above is based on assumptions that no operator has yet accomplished any of the 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 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 final evaluation has been prepared for this action and it is contained in the Rules Docket. A copy of it may be obtained from 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 delegatedto 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 the following new airworthiness directive: