AD 97-10-05

This amendment adopts a new airworthiness directive (AD) that applies to certain Jetstream Aircraft Limited (JAL) HP137 Mk1, Jetstream series 200, and Jetstream Models 3101 and 3201 airplanes. This AD requires repetitively inspecting the main landing gear (MLG) pintle to cylinder interface area for cracks, and replacing any MLG cylinder where a crack of any length is found in the MLG pintle to cylinder interface area. This AD results from reports of MLG cracks in the area of the pintle to cylinder interface on three of the affected airplanes. The actions specified by this AD are intended to prevent failure of the MLG caused by cracks in the pintle to cylinder interface area, which could result in loss of control of the airplane during landing operations.

Final rule

97-10-05 JETSTREAM AIRCRAFT LIMITED: Amendment 39-10017; Docket No. 95-CE-44-AD.
Applicability: HP 137 Mk1, Jetstream series 200, and Jetstream Models 3101 and 3201 airplanes (all serial numbers), certificated in any category, that are equipped with a main landing gear (MLG) incorporating one of the following part numbers (or FAA-approved equivalent):

1863
1863/4A,
1863/4B
1863/4C
1864
1864/4A
1864/4B
1864/4C
BOOA702850A
BOOA702851A
BOOA702925A
BO1A702925A
BOOA703065A
BO1A703065A
BOOA703030A
BOOA702926A
BO1A702926A
BOOA703066A
BO1A703066A
BOOA703031A

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 alternativemethod 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 initially upon accumulating 8,000 landings on an affected MLG or within the next 100 landings after the effective date of this AD, whichever occurs later, unless already accomplished, and thereafter at intervals not to exceed 1,200 landings accumulated on an affected MLG.

NOTE 2: If the number of landings is unknown, hours time-in-service (TIS) may be used by multiplying the number of hours TIS by 0.75. If hours TIS are utilized to calculate the number of landings, this would make the AD effective "initially upon accumulating 10,667 hours TIS on an affected MLG or within the next 133 hours TIS after the effective date of thisAD, whichever occurs later, and thereafter at intervals not to exceed to 1,600 hours TIS accumulated on an affected MLG."

To prevent failure of the MLG caused by cracks in the pintle to cylinder interface area, which could result in loss of control of the airplane during landing operations, accomplish the following:

(a) Inspect the MLG pintle to cylinder interface area for cracks in accordance with one of the following:

(1) Using non-destructive testing (NDT) eddy current methods, in accordance with AP Precision Hydraulics Ltd. Service Bulletin 32-56, Revision 3, dated February 1995; or

(2) Using fluorescent penetrant methods, in accordance with APPENDIX 1 in Jetstream Service Bulletin 32-JA 960142, dated March 15, 1996; or APPENDIX 2 in Jetstream Alert Service Bulletin 32-A-JA 941245, Revision 3, dated March 15, 1996, which incorporates the following pages:

Pages
Revision Level
Date
1 through 4
Revision 3
March 15, 1996
5 through 11
Revision 2
March 28, 1995

(b) If any crack is found during any inspection required by this AD, prior to further flight, replace the MLG cylinder with a serviceable part in accordance with the applicable maintenance manual. Replacing the MLG cylinder does not eliminate the repetitive inspection requirement of this AD.

NOTE 3: The "prior to further flight" replacement compliance time required by this AD if a MLG cylinder is cracked is different from the compliance times referenced in Jetstream Service Bulletin 32-JA 960142, dated March 15, 1996; Precision Hydraulics Ltd. Service Bulletin 32-56, Revision 3, dated February 1995, or Jetstream Alert Service Bulletin 32-A-JA 941245, Revision 3, dated March 15, 1996. This AD takes precedence over any service information.

(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 ADcan be accomplished.

(d) An alternative method of compliance or adjustment of the initial and repetitive compliance times that provides an equivalent level of safety may be approved by the Manager, Brussels Aircraft Certification Division, Europe, Africa, Middle East office, FAA, c/o American Embassy, B-1000 Brussels, Belgium. The request should be forwarded through an appropriate FAA Maintenance Inspector, who may add comments and then send it to the Manager, Brussels Aircraft Certification Division.

NOTE 4: Information concerning the existence of approved alternative methods of compliance with this AD, if any, may be obtained from the Brussels Aircraft Certification Division.

(e) The inspections required by this AD shall be done in accordance with either Jetstream Service Bulletin 32-JA 960142, dated March 15, 1996; Precision Hydraulics Ltd. Service Bulletin 32-56, Revision 3, dated February 1995; or Jetstream Alert Service Bulletin 32-A-JA 941245, Revision 3, datedMarch 15, 1997, which incorporates the following pages:

Pages
Revision Level
Date
1 through 4
Revision 3
March 15, 1996
5 through 11
Revision 2
March 28, 1995

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 Limited, Manager Product Support, Prestwick Airport, Ayrshire, KA9 2RW Scotland; or Jetstream Aircraft Inc., Librarian, P.O. Box 16029, Dulles International Airport, Washington, DC, 20041-6029. Copies may be inspected at the FAA, Central Region, Office of the Assistant Chief 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.

(f) This amendment becomes effective on July 11, 1997.

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 certain JAL HP137 Mk1, Jetstream series 200, and Jetstream Models 3101 and 3201 airplanes was published in the Federal Register as a notice of proposed rulemaking (NPRM) on September 19, 1995 (60 FR 48429). The NPRM proposed to require repetitively inspecting the MLG pintle to cylinder interface area for cracks, and replacing any MLG cylinder where a crack is found in the MLG pintle to cylinder interface area that exceeds certain limits.

Interested persons were afforded an opportunity to participate in the making of this amendment. One comment was received in favor of the proposed rule and no comments were received regarding the FAA's determination of the cost to the public.

As written, the original NPRM would have allowed continued flight if cracks are found in the MLG pintle to cylinder interface area when the cracks do not exceed certain limits. Since issuing that NPRM, the FAA established a policy to disallow airplane operation when known cracks exist in primary structure, unless the ability to sustain ultimate load with these cracks is proven. This policy was established based on the FAA's extensive analysis of the consequences of flying with cracks in primary structure. The MLG pintle to cylinder interface area is considered primary structure, and the FAA has not received any analysis to prove that ultimate load can be sustained with cracks in this area.

For this reason, the FAA determined that the crack limits specified in the NPRM should be eliminated and that the NPRM should be revised to propose immediate replacement of the MLG cylinder if any cracks are found in the MLG pintle to cylinder interface area. Since revising the proposed AD to require immediate replacement of the MLG cylinder when cracks are found in the MLG pintle to cylinder interfacearea went beyond the scope of what was presented in the original NPRM, the FAA published a supplemental NPRM in the Federal Register on March 19, 1996 (61 FR 12051, March 25, 1996).

After publication of this supplemental NPRM, the FAA re-examined all information related to this subject and determined that the actions proposed were still a valid safety issue, but that more stringent repetitive inspection intervals needed to be established. Specifically, the MLG pintle to cylinder interface area would need to be inspected initially "upon accumulating 8,000 landings on an affected MLG." (instead of 8,500 landings), ". . . and, thereafter at intervals not to exceed 1,200 landings . . ." (instead of 4,000 landings). The more stringent inspection intervals were based on an analysis done by JAL and subsequently evaluated and approved by the FAA. The FAA issued another supplemental NPRM that was published in the Federal Register on December 17, 1996 (61 FR 66238) to incorporate the more stringent inspection intervals.

Interested persons were again afforded an opportunity to participate in the making of this amendment. No comments were received regarding the substance of the second supplemental NPRM 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 AD as proposed in the second supplemental NPRM, 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.

Relevant Service Information
Accomplishment of the inspections required by this AD are required in accordance with Jetstream Service Bulletin 32-JA 960142, dated March 15, 1996; AP Precision Hydraulics Ltd. Service Bulletin 32-56, Revision 3, datedFebruary 1995; and Jetstream Alert Service Bulletin 32-A-JA 941245, Revision 2, dated March 15, 1996, which incorporates the following pages:

Pages
Revision Level
Date

1 through 4
Revision 3
March 15, 1996
5 through 11
Revision 2
March 28, 1995

Cost Impact
The FAA estimates that 250 airplanes in the U.S. registry will be affected by this AD, that it will take approximately 6 workhours per airplane to accomplish this AD, and that the average labor rate is approximately $60 an hour. Based on these figures, the total cost impact of the required inspection on U.S. operators is estimated to be $90,000. This figure does not take into account the cost of repetitive inspections or the cost of replacement MLG cylinders if any crack is found in the MLG pintle to cylinder interface area. The FAA has no way of determining the number of repetitive inspections each owner/operator would incur over the life of the airplane or the number of MLG cylinders that may be found cracked during the inspections required by this AD.

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 USC 106(g), 40113, 44701.

39.13 [Amended]
2. Section 39.13 is amended by adding a new airworthiness directive (AD) to read as follows: