AD 96-11-02

This amendment adopts a new airworthiness directive (AD) that applies to Jetstream Aircraft Limited (JAL) HP137 Mk1, Jetstream series 200, and Jetstream Model 3101 airplanes. This action requires repetitively inspecting the spigot housing plate for cracks at the wing/fuselage forward attachment sliding joint, replacing any cracked housing plate, repetitively inspecting the spigots and spigot posts for corrosion and installing improved spigots if corrosion is found that exceeds certain limits, and eventually installing improved spigots if corrosion that does not exceed certain limits is found. For certain affected airplanes, this action requires repetitively inspecting the spigot bushes for migration gaps, replacing the bushes with modified bushes if gaps are found that exceed 0.5 inch, and eventually replacing the bushes with modified bushes if migration gaps are not found. Reports of bush migration gaps found on three of the affected airplanes and another report of corrosion and several cracks found on the spigot housing plate on a Jetstream Model 3101 airplane prompted this action. The actions specified by this AD are intended to prevent structural failure of the wing/fuselage area caused by a cracked or corroded spigot housing assembly.

Final rule

96-11-02 JETSTREAM AIRCRAFT LIMITED: Amendment 39-9627; Docket No. 95-CE-79-AD.
Applicability: HP137 Mk1, Jetstream series 200, and Jetstream Model 3101 airplanes (all serial numbers), certificated in any category.

Compliance: Required as indicated in the body of this AD, unless already accomplished.

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 (g) 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.

To prevent structural failure of the wing/fuselage area caused by a cracked spigot housing assembly, accomplish the following:

(a) For all affected airplanes, upon the accumulation of 7,200 hours time-in-service (TIS) or within the next 1,200 hours TIS after the effective date of this AD, whichever occurs later, and thereafter at intervals not to exceed 7,200 hours TIS, accomplish the following:

(1) Inspect the spigot housing plate at the wing/fuselage forward attachment sliding joint for cracks in accordance with Part 1 of the ACCOMPLISHMENT INSTRUCTIONS section of Jetstream Service Bulletin (SB) 57-JA 930941, Revision No. 2, dated November 11, 1994.

(2) If a cracked spigot housing plate is found, prior to further flight, replace the cracked spigot housing plate in accordance with Part 3 of the ACCOMPLISHMENT INSTRUCTIONS section of Jetstream SB 57-JA 930941, Revision No. 2, dated November 11, 1994.

(3) Replacing the spigot housing plate does not eliminate the 7,200-hour TIS interval repetitive inspection requirement.

(b) For all affected airplanes, within the next 12 calendar months after the effective date of this AD, and thereafter at intervals not to exceed 48 calendar months until Modification No. JM 5326 and Modification No. JM 5259 (as applicable) are incorporated as required by paragraphs (d)(1) and (d)(2) of this AD, inspect the spigots and spigot posts for corrosion in accordance with Part 2 of the ACCOMPLISHMENT INSTRUCTIONS section of Jetstream SB 57-JA 930941, Revision No. 2, dated November 11, 1994.

(1) If corrosion damage is found in the spigot post that is 0.06 inch (1.52 mm) or less deep and does not extend to within 0.9 inch (22.9 mm) from either end of the bore, prior to further flight, treat the corrosion in accordance with paragraph (8)(d) of the ACCOMPLISHMENT INSTRUCTIONS section of Jetstream SB 57-JA 930941, Revision No. 2, dated November 11, 1994.

(2) If corrosion damage in the spigot post is found that is more than 0.06 inch (1.52 mm) or extends to within 0.9 inch (22.9 mm) from either end of the bore, prior to further flight, obtain a repair scheme from the manufacturer through the Brussels Aircraft Certification Office (ACO) at the address specified in paragraph (g) of this AD, and incorporate this repair scheme.

(3) If corrosion damage in the spigot is found that penetrates the protective surface of the spigot, within four calendar months after finding the corrosion damage, replace both wing/fuselage spigots with new modified spigots (Modification No. JM 5326) in accordance with Jetstream SB 57-JM 5326, dated September 3, 1993. Modification No. JM 5326 incorporates a new P/N 13781B401 spigot assembly.

(c) For all affected HP137 Mk1 airplanes and all affected Jetstream series 200 airplanes, and Jetstream Model 3101 airplanes with a serial number in the range of 601 through 702 (inclusive), within the next 1,200 hours TIS after the effective date of this AD, inspect the wing/fuselage forward attachment spigot bushes for migration gaps in accordance with the ACCOMPLISHMENT INSTRUCTIONS section of BAe Jetstream Alert SB 57-A-JA 920640, dated February 19, 1993.

(1) If no migration gaps are found, reinspect at intervals not to exceed 4,500 hours TIS until Modification No. JM 5259 is incorporated. If migration gaps are found upon reinspection, install modified bushes as specified in paragraph (c)(2) or (c)(3) of this AD.

(2) If migration gaps are found that are 0.5 inch or less, reinspect at intervals not to exceed 900 hours TIS until Modification No. JM 5259 is incorporated. If migration gaps are found upon reinspection that are larger than .5 inch, accomplish paragraph (c)(3) of this AD, as applicable.

(3) If migration gaps are found that are larger than 0.5 inch, within 150 hours TIS after the last inspection required by paragraph (c) (1) or (c)(2) of this AD, install modified bushes at the wing/fuselage forward attachment spigots (Modification JM 5259) in accordance with the ACCOMPLISHMENT INSTRUCTIONS section of BAe Jetstream SB 57-JM 5259, dated February 5, 1993, and Erratum No. 1 to SB 57-JM 5259, dated February 8, 1993.

(d) Upon accumulating 25,000 hours TIS or within 1,000 hours TIS after the effective date of this AD, whichever occurs later, accomplish the following:

(1) For all affected HP137 Mk1, Jetstream series 200, and Jetstream Model 3101 airplanes, replace both wing/fuselage spigots with new modified spigots (Modification No. JM 5326) in accordance with Jetstream SB 57-JM 5326, dated September 3, 1993; and

(2) For all affected HP137 Mk1 airplanes and all affected Jetstream series 200 airplanes, and Jetstream Model 3101 airplanes with a serial number in the range of 601 through 702 (inclusive), install modified bushes at the wing/fuselage forward attachment spigots (Modification No. JM 5259) in accordance with the ACCOMPLISHMENT INSTRUCTIONS section of BAe Jetstream SB 57-JM 5259, dated February 5, 1993, and Erratum No. 1 to SB 57-JM 5259, dated February 8, 1993.

(3) Incorporating Modification No. JM 5259 eliminates the requirement of repetitively inspecting the wing/fuselage forward attachment spigot bushes for migration gaps as required by all designations of paragraph (c) of this AD.

(e) Incorporating both Modification No. JM 5326 and Modification No. JM 5259 eliminates the repetitive inspections required by all designations of paragraphs (b) and (c) of this AD. This does not eliminate the repetitive inspections of the spigot housing plate as required by paragraph (a) of this AD.

(f) 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.

(g) An alternative method of compliance or adjustmentof the initial or repetitive compliance times that provides an equivalent level of safety may be approved by the Manager, Brussels Aircraft Certification Office (ACO), Europe, Africa, Middle East office, FAA, c/o American Embassy, 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 ACO.

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

(h) The inspections required by this AD shall be done in accordance with BAe Jetstream Alert Service Bulletin 57-A-JA 920640, dated February 19, 1993; and Jetstream Service Bulletin 57-JA 930941, Revision 2, dated November 11, 1994. The modifications required by this AD shall be done in accordance with BAe Jetstream Service Bulletin 57-JM 5259, dated February 5, 1993, and Erratum No. 1 to Service Bulletin 57-JM 5259, dated February 8, 1993; and Jetstream Service Bulletin 57-JM 5326, dated September 3, 1993. 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.

(i) This amendment becomes effective on July 2, 1996.

Events Leading to the AD
A proposal to amend part 39 of the Federal Aviation Regulations (14 CFR part 39) to include an AD that would apply to JAL HP137 Mk1, Jetstream series 200, and Jetstream Model 3101 airplanes was published in the Federal Register on January 19, 1996 (61 FR 1295). The action proposed to require repetitively inspecting the spigot housing plate for cracks at the wing/fuselage forward attachment sliding joint, replacing any cracked housing plate, repetitively inspecting the spigots and spigot posts for corrosion and installing improved spigots if corrosion is found, and eventually installing improved spigots if corrosion is not found. For certain affected airplanes, the proposed action would require repetitively inspecting the spigot bushes for migration gaps, replacing the bushes with modified bushes if gaps are found that exceed 0.5 inch, and eventually replacing the bushes with modified bushes if migration gaps are not found. Accomplishment of the proposed inspections would be in accordance with BAe Jetstream Alert Service Bulletin (ASB) 57-A-JA 920640, dated February 19, 1993; and Jetstream Service Bulletin (SB) 57-JA 930941, Revision 2, dated November 11, 1994. Accomplishment of the proposed modifications would be in accordance with BAe Jetstream SB 57-JM 5259, dated February 5, 1993, and Erratum No. 1 to SB 57-JM 5259, dated February 8, 1993; and Jetstream SB 57-JM 5326, dated September 3, 1993.

Interested persons have been afforded an opportunity to participate in the making of this amendment. Due consideration has been given to the comments received from two different commenters. One of these commenters supports the proposal as written.

Comment Resolution
JAL states that the corrosion limits specified in paragraphs (b)(1) and (b)(2) of the AD only specify the spigot posts. JAL further states that Jetstream SB 57-JA 930941, Revision No. 2, dated November 11, 1994, also specifies corrosion limitsfor the spigots. JAL requests that these corrosion limits and applicable service bulletin instructions be added to the final rule. The FAA concurs and has revised the AD accordingly.

JAL also recommends that the repetitive inspection interval be changed to 48 calendar months instead of 12 calendar months to coincide with Jetstream SB 57-JA 93041. The FAA established the initial inspection in the proposal at 12 calendar months and meant to establish the repetitive inspection interval at 48 calendar months, but inadvertently established the repetitive inspection interval at 12 calendar months. The FAA's analysis of data initially submitted by JAL indicates that repetitively inspecting the spigot housing area for cracks and corrosion at 48 calendar month intervals provides the level of safety necessary to correct the unsafe condition. The final rule AD has been revised to reflect this change.

JAL asks whether an owner/operator who found a cracked spigot housing plate couldapply for an alternative method of compliance to allow 150 flight hours before installation rather than prior to further flight when a crack is found that is shorter than 0.2 inch. JAL states that this would allow the owner/operator of the affected airplane time to obtain the necessary parts, and also states that fatigue tests have demonstrated slow crack growth. The FAA allows any owner/operator to submit a request for an alternative method of compliance, including an extension of the compliance time. The owner/operator should submit the request with all substantiating data in accordance with the provisions in the AD. The FAA will evaluate each request to determine whether the alternative method of compliance establishes an equivalent level of safety to the actions of the AD, and then will either approve or reject the request accordingly.

No comments were received regarding the FAA's estimate of the cost impact on the public.

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 the changes previously discussed and minor editorial corrections. The FAA has determined that these changes and minor corrections will not change the meaning of the AD and will not add any additional burden upon the public than was already proposed.

Aspects of the Action
The alternative to incorporating new modified spigots and bushes would be to require repetitive inspections. FAA aging commuter-class aircraft policy states that reliance on critical repetitive inspections carries an unnecessary safety risk when a design change exists that could eliminate or, in certain instances, reduce the number of those critical inspections. Therefore, the required spigot and bush replacements is consistent with the FAA's commuter-class aircraft policy.

The compliance times of the repetitive inspections of the spigots and spigot posts for corrosion and subsequent replacement, if necessary, are presented in calendar time instead of hours time-in-service (TIS). Corrosion can occur on airplanes regardless of whether the airplane is in service or in storage. Therefore, to ensure that corrosion is detected and corrected on all airplanes within a reasonable period of time without inadvertently grounding any airplanes, a compliance schedule based upon calendar time instead of hours TIS is utilized.

Cost Impact
The FAA estimates that 143 airplanes in the U.S. registry will be affected by this AD, that it will take approximately 61 workhours per airplane to accomplish the inspections and modifications, and that the average labor rate is approximately $60 an hour. Parts cost approximately $320 per airplane. Based on these figures, the total cost impact of this AD on U.S. operators is estimated to be $569,140 or $3,980 per airplane. This figure only takes into account the cost of initial inspections and does not take into account repetitive inspection costs. The FAA has no way of determining the number of repetitive inspections each affected airplane owner/operator will incur over the life of the airplane.

The approximately 61 workhours it will take to accomplish the required actions is based on each inspection and modification being accomplished separately. The FAA anticipates that many owners/operators of the affected airplanes will schedule all of the required actions to be accomplished at the same time, thereby reducing the labor costs associated with accomplishing these actions.

In addition, Jetstream Aircraft Limited has informed the FAA that parts have been distributed to equip approximately 40 airplanes. Assuming that each set of parts is installed on an affected HP137 Mk1, Jetstream series 200, or Jetstream Model 3101 airplane, the cost impact of this AD upon U.S. operators is reduced $159,200 from $569,140 to $409,940.

Regulatory Impact
The regulations adoptedherein 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 thelocation 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.

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