AD 98-13-03

This amendment supersedes Airworthiness Directive (AD) 82-20-04 R1, which currently requires repetitively inspecting the main landing gear (MLG) hinge fitting, support angles, and attachment bolts on British Aerospace H.P. 137 Mk1 and Jetstream series 200 airplanes, and repairing or replacing any part that is cracked beyond certain limits. This AD requires installing improved design MLG fittings, as terminating action for the repetitive inspections that are currently required by AD 82-20-04 R1, and will incorporate the Jetstream Model 3101 airplanes into the Applicability of the AD. The Federal Aviation Administration's policy on aging commuter-class aircraft is to eliminate or, in certain instances, reduce the number of certain repetitive short-interval inspections when improved parts or modifications are available. The actions specified by this AD are intended to prevent structural failure of the MLG caused by fatigue cracking, which could result in loss of control of the airplane during landing operations.

Final rule

98-13-03 BRITISH AEROSPACE (Type Certificate No. A21EU formerly held by Jetstream Aircraft Limited): Amendment 39-10591; Docket No. 95-CE-53-AD; Supersedes AD 82-20- 04 R1, Amendment 39-4468.
Applicability: The following model and serial number airplanes, certificated in any category, that do not have improved design main landing gear (MLG) fittings, part number (P/N) 1379133B1 and 1379133B2 (Modification 5218), installed in accordance with Jetstream Service Bulletin (SB) 57-JM 5218:

Model
Serial Numbers
H.P. 137 MK1
all serial numbers
Jetstream Series 200
all serial numbers
Jetstream Model 3101
601 through 695

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 (f) 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 after the effective date of this AD, unless already accomplished.

To prevent structural failure of the MLG caused by fatigue cracking, which could result in loss of control of the airplane during landing operations, accomplish the following:

NOTE 2: The compliance times of this AD are presented in landings. If the total number of airplane landings is not kept or is unknown, hours time-in-service (TIS) may be used by multiplying the total number of airplane hours TIS by 0.75.

(a) For the H.P. 137 MK1 and Jetstream series 200 airplanes, within the next 50landings after the effective date of this AD or within 200 landings after the last inspection required by AD 82-20-04 R1 (superseded by this AD), whichever occurs first, and thereafter at intervals not to exceed 200 landings, accomplish the following in accordance with British Aerospace Mandatory Service Bulletin (MSB) No. 7/5, which incorporates the following pages:

Pages
Revision Level
Date
2 and 4
Original Issue
March 31, 1982
1 and 3
Revision 1
May 23, 1988

(1) Inspect the MLG hinge attachment nuts to auxiliary and aft spars on both the left and right MLG for signs of fuel leakage or signs of relative movement between the nuts and hinge fitting.

(2) If any signs of fuel leakage or relative movement between the nuts and hinge fitting are found, prior to further flight, resecure the MLG hinge fitting to auxiliary spar in accordance with actions 3.8 through 3.16 of British Aerospace MSB No. 7/5.

(b) Upon accumulating 4,000 landings on the left and right MLG fittings or within the next 50 landings after the effective date of this AD, whichever occurs later, and thereafter at intervals not to exceed 400 landings, inspect the MLG hinge support angles for cracks in accordance with the following, as applicable:

(1) For the H.P. 137 MK1 and Jetstream series 200 airplanes: British Aerospace MSB 7/8, which incorporates the following effective pages:

Pages
Revision Level
Date
2, 5, 6, 7, and 8
Revision 2
January 6, 1983
1, 3, and 4
Revision 3
May 23, 1988

(2) For the Jetstream Model 3101 airplanes: Jetstream Alert Service Bulletin (ASB) 32-A-JA 850127, which incorporates the following effective pages:

Pages
Revision Level
Date
5 through 14
Original Issue
April 17, 1985
1 through 4
Revision 2
November 11, 1994

(c) Install improved design MLG fittings, part number (P/N) 1379133B1 and 1379133B2 (Modification 5218), as applicable. Perform these installations at the applicable compliance time presented below (paragraphs (c)(1) and (c)(2) of this AD). Accomplish this installation in accordance with Jetstream Service Bulletin (SB) 57-JM 5218, which incorporates the following effective pages:

Pages
Revision Level
Date
3, 5, 6, 7, 8, 9,
11, 12, 17, 18,
19, 21, 22, 23,
24, 27, 28, 29,
30, and 31
Revision 1
September 29, 1987
25 and 26
Revision 2
August 24, 1988
10 and 20
Revision 3
January 29, 1990

1, 2, 4, 13, 14,
15, and 16
Revision 4
October 31, 1990

(1) Prior to further flight on any fitting found cracked during an inspection required by paragraph (b) of this AD; and

(2) Upon accumulating 20,000 landings on the left MLG fitting or within the next 50 landings after the effective date of this AD (whichever occurs later), unless already accomplished as required by paragraph (c)(1) of this AD; and

(3) Upon accumulating 20,000 landings on the right MLG fitting or within the next 50 landings after the effective date of thisAD (whichever occurs later), unless already accomplished as required by paragraph (c)(1) of this AD.

(d) Incorporating both P/N 1379133B1 and P/N 1379133B2 MLG fittings (Modification 5218) as required by paragraph (c), including all subparagraphs, of this AD terminates the repetitive inspection requirement of paragraph (a) of this AD. The repetitive inspections of the MLG support angles required by paragraph (b) of this AD are still required.

(e) 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.

(f) An alternative method of compliance or adjustment of the initial or repetitive compliance times that provides an equivalent level of safety may be approved by the Manager, Small Airplane Directorate, 1201 Walnut, suite 900, Kansas City, Missouri 64106.

(1) 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.

(2) Alternative methods of compliance approved in accordance with AD 82-20-04 R1 (superseded by this action) are not considered approved as alternative methods of compliance with this AD.

NOTE 3: Information concerning the existence of approved alternative methods of compliance with this AD, if any, may be obtained from the Small Airplane Directorate.

(g) Questions or technical information related to the service information referenced in this AD should be directed to British Aerospace Regional Aircraft, Prestwick International Airport, Ayrshire, KA9 2RW, Scotland; telephone: (01292) 479888; facsimile: (01292) 671715. 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.

(h) The inspections, modifications, and installationsrequired by this AD shall be done in accordance with the following:

- British Aerospace Jetstream Mandatory Service Bulletin No. 7/5, which incorporates the following pages:

Pages
Revision Level
Date
2 and 4
Original Issue
March 31, 1982
1 and 3
Revision 1
May 23, 1988

- British Aerospace Mandatory Service Bulletin No. 7/8, which incorporates the following effective pages:

Pages
Revision Level
Date
2, 5, 6, 7, and 8
Revision 2
January 6, 1983
1, 3, and 4
Revision 3
May 23, 1988

- Jetstream Alert Service Bulletin 32-A-JA 850127, which incorporates the following effective pages:

Pages
Revision Level
Date
5 through 14
Original Issue
April 17, 1985
1 through 4
Revision 2
November 11, 1994

- Jetstream Service Bulletin 57-JM 5218, which incorporates the following effective pages:

Pages
Revision Level
Date
3, 5, 6, 7, 8, 9,
11, 12, 17, 18,
19, 21, 22, 23,
24, 27, 28, 29,
30, and 31
Revision 1
September 29, 1987
25 and 26
Revision 2
August 24, 1988
10 and 20
Revision 3
January 29, 1990
1, 2, 4, 13, 14,
15, and 16
Revision 4
October 31, 1990

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.

(i) This amendment supersedes AD 82-20-04 R1, Amendment 39-4468.

(j) This amendment becomes effective on August 3, 1998

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 British Aerospace (Operations) Limited H.P. 137 Mk1, Jetstream series 200, and Jetstream Model 3101 airplanes was published in the Federal Register as a supplemental notice of proposed rulemaking (NPRM) on March 4, 1998 (63 FR 10579). The supplemental NPRM proposed to supersede AD 82-20-04 R1 with a new AD that would: (1) initially retain the requirements contained in AD 82-20-04 R1 of repetitively inspecting the MLG hinge fitting, support angles, and attachment bolts, and repairing or replacing any part that is cracked; (2) incorporate the Jetstream Model 3101 airplanes into the Applicability of the AD; and (3) eventually require the installation of improved design MLG fittings, part number (P/N) 1379133B1 and 1379133B2 (Modification 5218), as terminating action for the repetitive inspections.Accomplishment of this action would be in accordance with the following service information:

- British Aerospace Jetstream Mandatory Service Bulletin (MSB) No. 7/5, which includes procedures for inspecting the left and right main landing gear hinge attachment nuts to the auxiliary and aft spars for signs of relative movement between the nuts and hinge fitting on H.P. 137 MK1 and Jetstream series 200 airplanes. This MSB incorporates the following effective pages:

Pages
Revision Level
Date
2 and 4
Original Issue
March 31, 1982
1 and 3
Revision 1
May 23, 1988

- British Aerospace MSB No. 7/8, which includes procedures for inspecting the MLG hinge fitting for cracks, and repairing cracked hinge fittings on H.P. 137 MK1 and Jetstream series 200 airplanes. This MSB incorporates the following effective pages:

Pages
Revision Level
Date
2, 5, 6, 7, and 8
Revision 2
January 6, 1983
1, 3, and 4
Revision 3
May 23, 1988

- Jetstream Alert Service Bulletin (ASB) 32-A-JA 850127, which includes procedures for inspecting the MLG hinge fitting and support angle for cracks on Jetstream Model 3101 airplanes. This ASB incorporates the following effective pages:

Pages
Revision Level
Date
5 through 14
Original Issue
April 17, 1985
1 through 4
Revision 2
November 11, 1994

- Jetstream Service Bulletin (SB) 57-JM 5218, which includes procedures for installing improved design MLG fittings, part number (P/N) 1379133B1 and 1379133B2 (Modification 5218), on H.P. 137 Mk1, Jetstream series 200, and certain Jetstream Model 3101 airplanes. This SB incorporates the following effective pages:

Pages
Revision Level
Date
3, 5, 6, 7, 8, 9,
11, 12, 17, 18,
19, 21, 22, 23,
24, 27, 28, 29,
30, and 31
Revision 1
September 29, 1987
25 and 26
Revision 2
August 24, 1988
10 and 20
Revision 3
January 29, 1990
1, 2, 4, 13, 14,
15, and 16
Revision 4
October 31, 1990

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.

Differences Between this AD, the British AD, and AD 82-20-04 R1
AD 82-20-04 R1 allows continued flight if cracks are found in the MLG hinge fitting support angles that propagate no further than the tooling holes. The applicable service bulletin specifies replacement of the support angles only if cracks are found exceeding this limit, as does British AD 015-05-85. This AD will not allow continuedflight if any crack is found. FAA policy is to disallow airplane operation when known cracks exist in primary structure, unless the ability to sustain ultimate load with these cracks is proven, and then this is only considered a temporary solution until a design correction is developed and incorporated. The main landing gear 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.

The FAA's Aging Commuter Aircraft Policy
The actions required by this AD are consistent with the FAA's aging commuter aircraft policy, which briefly states that, when a modification exists that could eliminate or reduce the number of required critical inspections, the modification should be incorporated. This policy is based on the FAA's determination that reliance on critical repetitive inspections on airplanes utilized in commuter service carries an unnecessary safety risk when a design change exists that could eliminate or, in certain instances, reduce the number of those critical inspections. In determining what inspections are critical, the FAA considers (1) the safety consequences of the airplane if the known problem is not detected by the inspection; (2) the reliability of the inspection such as the probability of not detecting the known problem; (3) whether the inspection area is difficult to access; and (4) the possibility of damage to an adjacent structure as a result of the problem.

The alternative to installing improved design MLG fitting would be to repetitively inspect this area for the life of the airplane.

Cost Impact
The FAA estimates that 71 airplanes in the U.S. registry will be affected by this AD, that it will take approximately 271 workhours (inspections: 61 workhours; installation: 210 workhours) per airplane to accomplish these actions, and that the average labor rate is approximately $60 an hour. Parts to accomplish this AD are provided by the manufacturer at no cost to the owners/operators of the affected airplanes. Based on these figures, the total cost impact of this AD on U.S. operators is estimated to be $1,154,460, or $16,260 per airplane. This figure only takes into account the cost of the initial inspections and inspection-terminating modification and does not take into account the cost of repetitive inspections. The FAA has no way of determining the number of repetitive inspections each H.P. 137 Mk1, Jetstream series 200, and Jetstream Model 3101 airplane owner/operator will incur.

This figure is also based on the presumption that no affected airplane operator has accomplished this installation. This action will eliminate the repetitive inspections required by AD 82-20-04 R1. The FAA has no way of determining the operation levels of each individual owner/operator of the affected airplanes, and cannot determine the repetitive inspection costs that will be eliminated by this action. The FAA estimates these costs to be substantial over the long term.

In addition, British Aerospace has informed the FAA that parts have been distributed to owners/operators that will equip approximately 39 of the affected airplanes. Presuming that each set of parts has been installed on an affected airplane, the cost impact of this modification upon the public will be reduced $634,140 from $1,154,460, to $520,320.

Regulatory Flexibility Determination and Analysis
The Regulatory Flexibility Act of 1980 (RFA) was enacted by Congress to ensure that small entities are not unnecessarily or disproportionally burdened by government regulations. The RFA requires government agencies to determine whether rules would have a "significant economic impact on a substantial number of small entities," and, in cases where they would, conduct a Regulatory Flexibility Analysis in which alternatives to the rule are considered. FAA Order 2100.14A, Regulatory Flexibility Criteria and Guidance, outlines FAA procedures and criteria for complying with the RFA. Small entities are defined as small businesses and small not-for-profit organizations that are independently owned and operated or airports operated by small governmental jurisdictions. A "substantial number" is defined as a number that is not less than 11 and that is more than one-third of the small entities subject to a proposed rule, or any number of small entities judged to be substantial by the rulemaking official. A "significant economic impact" is defined by an annualized net compliance cost, adjusted for inflation, which is greater than a threshold cost level for defined entity types.

FAA Order 2100.14A, Regulatory Flexibility Criteria and Guidance, defines a small entity as "a small business or small not-for-profit organization which is independently-owned and operated and has no more than a specified number of employees or aircraft." For operators of aircraft for hire (those entities that are affected by parts 121, 127, and 135 of the Federal Aviation Regulations (14 CFR parts 121, 127, and 135)), the size threshold specified in FAA Order 2100.14A is nine aircraft.

There are only nine different operators of British Aerospace H.P. 137 MK1, Jetstream series 200, and Jetstream Model 3101 airplanes. Of these nine, only four operate less than nine airplanes. Because 4 is a number that is less than 11 and the rulemaking official has not determined this number to be substantial, this AD would not significantly affect a number of small entities.

A copy of the full Cost Analysis and Regulatory Flexibility Determination for this action may be examined at the FAA, Central Region, Office of the Regional Counsel, Attention: Rules Docket No. 95-CE-53-AD, Room 1558, 601 E. 12th Street, Kansas City, Missouri.

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 removing Airworthiness Directive (AD) 82-20-04 R1, Amendment No. 39-4468, and by adding a new AD to read as follows: