AD 99-09-12

This amendment adopts a new airworthiness directive (AD), applicable to all British Aerospace (Jetstream) Model 4101 series airplanes, that requires repetitive inspections to detect damage of the structure associated with the engine nacelle fairing attached to the wing flaps, and repair of any damage found; drilling a new drain hole in each engine nacelle fairing; and applying a sealant to the gap between the wing flap and engine nacelle fairing. This amendment also requires correction of discrepancies, and modification of the wing flap structure, which terminates the repetitive inspections. This amendment is prompted by reports of fatigue cracks found in the structure that attaches the engine nacelle fairing to the wing flaps. The actions specified by this AD are intended to prevent such fatigue cracking, which could result in the partial or complete separation of the fairing from the wing flap, and consequent additional structural damage to the airframe and/or reduced controllability of the airplane.

Final rule

99-09-12 BRITISH AEROSPACE REGIONAL AIRCRAFT [Formerly Jetstream Aircraft Limited; British Aerospace (Commercial Aircraft) Limited]: Amendment 39-11145. Docket 96-NM-214-AD.
Applicability: Jetstream Model 4101 airplanes, excluding those on which Jetstream Modifications JM41575B and JM41575C have been accomplished, 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 actions to address it.

Compliance: Required as indicated, unless accomplished previously.

To prevent fatigue cracking in the structure that attaches the flap nacelle fairing to the wing flaps, which could result in the partial or complete separation of the fairing from the wing flap, and consequent additional structural damage to the airframe and/or reduced controllability of the airplane, accomplish the following:

(a) Prior to the accumulation of 1,500 total hours time-in-service, or within 60 days after the effective date of this AD, whichever occurs later, accomplish the requirements of paragraphs (a)(1), (a)(2), and (a)(3) of this AD.

(1) Perform a detailed visual inspection to detect discrepancies [cracks, loose rivets and Jo-Bolts, chafing damage at the flap trailing edge, and installation of nonstandard parts (as defined in Figure 1. of Jetstream Alert Service Bulletin J41-A57-015, Revision 1, dated August 23 1996, or Revision 2, dated June 30, 1997)] and previous repairs of the flap structure that attaches the flap nacelle fairing to each wing flap; in accordance with Jetstream Alert Service Bulletin J41-A57-015, Revision 1, dated August 23, 1996, or Revision 2, dated June 30, 1997. Repeat the inspection thereafter at intervals not to exceed 1,500 hours time-in-service until the requirements of paragraph (b) of this AD have been accomplished.

(i) Except as provided by paragraph (a)(1)(ii) of this AD, if any discrepancy is found, prior to further flight, perform corrective action in accordance with Revision 1 or Revision 2 of the alert service bulletin.

(ii) If any discrepancy is found for which Revision 1 or Revision 2 of the alert service bulletin specifies to contact the manufacturer to obtain a repair scheme: Prior to further flight, repair in accordance with a method approved by either the Manager, International Branch, ANM-116, FAA, Transport Airplane Directorate; or the Civil Aviation Authority (or its delegated agent).

(2) Drill a drain hole in the flap nacelle fairing on each wing flap, in accordance with Jetstream Alert Service Bulletin J41-A57-015, dated May 27, 1996, Revision 1, dated August 23, 1996, or Revision 2, dated June 30, 1997.

(3) Apply new primer and sealant to the gap between the wing flap and flap nacelle fairing, in accordance with Jetstream Alert Service Bulletin J41-A57-015, Revision 1, dated August 23, 1996, or Revision 2, dated June 30, 1997.

(b) Within 3,000 hours time-in-service after the effective date of this AD: Modify the wing flap structure in accordance with Jetstream Service Bulletin J41-57-017, dated May 9, 1997. Accomplishment of this modification constitutes terminating action forthe repetitive inspection requirements of this AD.

Alternative Methods of Compliance

(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, 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.

Special Flight Permits

(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.

Incorporation by Reference

(e)Except as provided by paragraph (a)(1)(ii) of this AD, the actions shall be done in accordance with Jetstream Service Bulletin J41-57-017, dated May 9, 1997; Jetstream Alert Service Bulletin J41-A57-015, Revision 1, dated August 23, 1996; and Jetstream Alert Service Bulletin J41-A57-015, Revision 2, dated June 30, 1997, which contains the following list of effective pages:

Page Number
Revision Level Shown on Page
Date Shown on Page
1-3
2
June 30, 1997
2, 4-9
1
August 23, 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 AI(R) American Support, Inc., 13850 Mclearen Road, Herndon, Virginia 20171. 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.

NOTE 3: The subject of thisAD is addressed in British airworthiness directive 006-05-96.

(f) This amendment becomes effective on June 1, 1999.

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 all British Aerospace (Jetstream) Model 4101 series airplanes was published as a supplemental notice of proposed rulemaking (NPRM) in the Federal Register on February 17, 1999 (64 FR 7830). That action proposed to require repetitive inspections to detect damage of the structure associated with the engine nacelle fairing attached to the wing flaps, and repair of any damage found; drilling a new drain hole in each engine nacelle fairing; and applying a sealant to the gap between the wing flap and engine nacelle fairing. That action also proposed to limit the applicability of the AD. The action also proposed to require corrective actions for discrepancies, and modification of the wing flap structure, which would terminate the repetitive inspections.

Comments
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 51 airplanes of U.S. registry will be affected by this AD.

It will take approximately 2 work hours per airplane to perform the detailed visual inspection, at an average labor rate of $60 per work hour. Based on these figures, the cost impact of the inspection required by this AD on U.S. operators is estimated to be $6,120, or $120 per airplane, per inspection cycle.

It will take approximately 1 work hour per airplane to drill a drain hole and apply primer and sealant, at an average labor rate of $60 per work hour. Based on these figures, the cost impact of these actions required by this AD on U.S. operators is estimated to be $3,060, or $60 perairplane.

It will take approximately 90 work hours per airplane to accomplish the required terminating modification, at an average labor rate of $60 per work hour. Required parts will cost approximately $2,658 per airplane. Based on these figures, the cost impact of the modification required by this AD on U.S. operators is estimated to be $410,958, or $8,058 per airplane.

The cost impact figures discussed above are 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 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 the following new airworthiness directive: