AD 94-18-05

This amendment adopts a new airworthiness directive (AD), applicable to certain Saab Model SF340A and SAAB 340B series airplanes. This amendment requires inspections to detect discrepancies of certain main landing gear (MLG) retract actuator bracket retaining bolts; replacement of discrepant parts; installation of washers, if necessary; and eventual replacement of certain MLG retract actuator bracket retaining bolts and certain nose landing gear (NLG) trunnion pin cross bolts. This amendment is prompted by reports of extension and retraction problems on the MLG, due to loose retract actuator brackets on the MLG shock struts. The actions specified by this AD are intended to prevent a loose retract actuator bracket from interfering with the MLG shock strut trunnion support, which could result in the inability of the MLG to extend or retract.

Final rule

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[4910-13-U]

DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 93-NM-234-AD; Amendment 39-9018; AD 94-18-05]

Airworthiness Directives; Saab Model SF340A and SAAB 340B Series Airplanes

AGENCY: Federal Aviation Administration, DOT.

ACTION: Final rule; correction.

SUMMARY: This document corrects a typographical error that appeared in the above-captioned airworthiness directive (AD), applicable to certain Saab Model SF340A and SAAB 340B series airplanes. That AD currently requires inspections to detect discrepancies of certain main landing gear (MLG) retract actuator bracket retaining bolts; replacement of discrepant parts; installation of washers, if necessary; and eventual replacement of certain MLG retract actuator bracket retaining bolts and certain nose landing gear (NLG) trunnion pin cross bolts. This action corrects terms in the compliance time specified for the requirement to remove the NLG trunnion pin cross bolts. This action is necessary to ensure that operators are not required to perform actions at a time that does not correspond with scheduled maintenance. DATES: Effective October 11, 1994.
The incorporation by reference of certain publications listed in the regulations was previously approved by the Director of the Federal Register as of October 11, 1994 (59 FR 46543, September 9, 1994). ADDRESSES: The service information referenced in this AD may be obtained from Saab Aircraft AB, Product Support, S581.88, Link ping, Sweden. This information may be examined at the Federal Aviation Administration (FAA), Transport Airplane Directorate, Rules Docket, 1601 Lind Avenue, SW., Renton, Washington; or at the Office of the Federal Register, 800 North Capitol Street, NW., suite 700, Washington, DC. FOR FURTHER INFORMATION CONTACT: Mark Quam, Aerospace Engineer, Standardization Branch, ANM-113, FAA, Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton, Washington 98055-4056; telephone (206) 227-2145; fax (206) 227-1320. SUPPLEMENTARY INFORMATION: On August 24, 1994, the FAA issued AD 94-18-05, amendment 39-9018 (59 FR 46543, September 9, 1994), to require inspections to detect discrepancies of certain main landing gear (MLG) retract actuator bracket retaining bolts; replacement of discrepant parts; installation of washers, if necessary; and eventual replacement of certain MLG retract actuator bracket retaining bolts and certain nose landing gear (NLG) trunnion pin cross bolts. That action was prompted by reports of extension and retraction problems on the MLG, due to loose retract actuator brackets on the MLG shock struts. The actions required by that AD are intended to prevent a loose retract actuator bracket from interfering with the MLG shock strut trunnion support, which could result in the inability of the MLG to extend or retract.
Recently, the FAAhas become aware of a typographical error that appeared in paragraph (c) of the published final rule, which would incorrectly require operators to replace the NLG trunnion pin cross bolts at a time that may not correspond with scheduled maintenance for the NLG. The compliance time for paragraph (c) was incorrectly published as, "At the next MLG overhaul, or within 12,000 landings after the effective date of the AD, whichever occurs earlier. . ." However, the correct compliance time for that requirement should have referred to ". . .at the next NLG overhaul."
Since it is essential that operators perform the replacement in a timely manner and at a time when the NLG is normally serviced, this document corrects the compliance terms of paragraph (c) of AD 94-18-05, amendment 39-9018, to read as follows:
"(c) At the next NLG overhaul, or within 12,000 landings after the effective date of this AD, whichever occurs earlier, remove the existing nose landing gear trunnion pin cross bolt, P/N NAS 1305-54D, and replace it with a new bolt, P/N NAS 1305-50D, in accordance with Paragraphs C. through F. of the Accomplishment Instructions of Saab Service Bulletin 340-32-094, dated October 29, 1993, or Revision 1, dated March 4, 1994."
The effective date of the rule remains October 11, 1994.
Since no other portion of the regulatory information has been changed, the final rule is not being republished.

94-18-05 SAAB AIRCRAFT AB: Amendment 39-9018. Docket 93-NM-234-AD.
Applicability: Saab Model SF340A series airplanes, serial numbers 004 through 159, inclusive; and SAAB 340B series airplanes, serial numbers 160 through 346, inclusive; certificated in any category.
Compliance: Required as indicated, unless accomplished previously.
To prevent the inability of the main landing gear (MLG) to extend or retract, accomplish the following:
(a) Within 600 landings after the effective date of this AD, or within 120 days after the effective date of this AD, whichever occurs earlier, accomplish the requirements of paragraphs (a)(1) and (a)(2) in accordance with Paragraphs 2.A. and 2.B. of the Accomplishment Instructions of Saab Service Bulletin 340-32-094, dated October 29, 1993, or Revision 1, dated March 4, 1994.
(1) Perform a visual inspection of each MLG retract actuator bracket retaining bolt, Item 792A or 792 [part number (P/N) AIR 124792], as applicable, to detect corrosion, cracking, or damage, in accordance with the service bulletin. If any corrosion, cracking, or damage is detected during that inspection, prior to further flight, replace the existing bolt with a new or serviceable bolt in accordance with the service bulletin.
(2) Perform a visual inspection of each MLG retract actuator bracket retaining bolt, Item 840 (P/N AIR 123940), to determine if the nut of the bolt is bottoming the threads in accordance with the service bulletin. If any nut bottoms the threads, prior to further flight, install washers in accordance with the service bulletin.
(b) At the next MLG overhaul, or within 12,000 landings after the effective date of this AD, whichever occurs earlier, accomplish the requirements of paragraphs (b)(1) and (b)(2) of this AD in accordance with Paragraphs C. through F. of the Accomplishment Instructions of Saab Service Bulletin 340-32-094, dated October 29, 1993, or Revision 1, dated March 4, 1994.
(1) Perform a visual and magnaflux inspection of each MLG retract actuator bracket retainer bolt, Item 792A or 792 (P/N AIR 124792), as applicable, to detect any scored, cracked, or out-of-tolerance condition, in accordance with the service bulletin. If any bolt is found to be scored, cracked, or out-of-tolerance, prior to further flight, replace the bolt with a serviceable magnafluxed bolt or with a new bolt, in accordance with the service bulletin.
NOTE 1: In accordance with normal maintenance practices, the retainer bolts also should be visually inspected for corrosion when they are removed during the accomplishment of the inspections required by this paragraph. Any corroded bolt that is detected should be replaced with a serviceable bolt or a new bolt. Instructions for performing visual inspections of the retainer bolts to detect corrosion are contained in Attachments 1, 2, 5, 6, and 7 of Saab Service Bulletin 340-32-094.
(2) Replace each existing MLG retract actuator bracket retaining bolt, Item 840 (P/N AIR 123940), with a new bolt, P/N AIR 134736, in accordance with the service bulletin.
(c) At the next NLG overhaul, or within 12,000 landings after the effective date of this AD, whichever occurs earlier, remove the existing nose landing gear trunnion pin cross bolt, P/N NAS 1305-54D, and replace it with a new bolt, P/N NAS 1305-50D, in accordance with Paragraphs C. through F. of the Accomplishment Instructions of Saab Service Bulletin 340-32-094, dated October 29, 1993, or Revision 1, dated March 4, 1994.
(d) 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 Manager, Standardization Branch, ANM-113.
(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) The actions shall be done in accordance with the following Saab service bulletins, which contain the following list of effective pages:

Saab Service
Bulletin and Date

Page NumberRevision Level
Shown on Page

Date
Shown on Page
340-32-094,
October 29, 1993
Title page
1-5
Original
(These pages are not dated.)
October 29, 1993

ATTACHMENT 1

1-4
Original
April 1993

ATTACHMENT 2

1-4
Original
April 1993

ATTACHMENT 3

1-6
Original
August 1993

ATTACHMENT 4

1-6
Original
August 1993

ATTACHMENT 5

1, 3
(These pages are not dated.)

2, 4
Original
June 1993

ATTACHMENT 6

1-4
(These pages are not dated.)

ATTACHMENT 7

1-4
(These pages are not dated.)

ATTACHMENT 8

1-4
(These pages are not dated.)

340-32-094,
Title page
1
March 4, 1994
Revision 1,
March 4, 1994
1-6
1
March 4, 1994

ATTACHMENT 1

2, 4
1
January 1994

1, 3
Original
April 1993

ATTACHMENT 2

2, 4
1
January 1994

1, 3
Original
April 1993

ATTACHMENT 3

1-4, 6-7
1
January 1994

5
Original
August 1993

ATTACHMENT 41-4, 6-7
1
January 1994

5
Original
August 1993

ATTACHMENT 5

1-5
2
January 1994

ATTACHMENT 6

1-5
2
January 1994

ATTACHMENT 7

1-5
2
January 1994

ATTACHMENT 8

1-5
2
January 1994

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 Saab Aircraft AB, Product Support, S581.88, Link ping, Sweden. 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.
(g) This amendment becomes effective on October 11, 1994.

FOR FURTHER INFORMATION CONTACT: Mark Quam, Aerospace Engineer, Standardization Branch, ANM-113, FAA, Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton, Washington 98055-4056; telephone (206) 227-2145; fax (206) 227-1320.

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 Saab Model SF340A and SAAB 340B series airplanes was published in the Federal Register on March 24, 1994 (59 FR 13898). That action proposed to require a one-time visual inspection to detect corrosion, cracking, or damage of certain MLG retract actuator bracket retaining bolts and to determine if the nut is bottoming the threads of certain other bolts; replacement of any discrepant bolt; and the installation of washers, if any nut is found bottoming the threads. It also proposed to require a one-time visual and magnaflux inspection during MLG overhaul to detect any scored, cracked, or out-of-tolerance condition of certain MLG retract actuator bracket retainer bolts; replacement of any discrepant bolt; and eventual replacement of certain MLG retract actuator bracket retaining bolts and certain NLG trunnion pin cross bolts.

Interested persons have been afforded an opportunity to participate in the making of this amendment. Due consideration has been given to the comments received.

One commenter supports the proposal.

Another commenter requests that the proposed rule be revised to include reference to Revision 1 of the specified Saab service bulletin. The FAA concurs. Since issuance of the notice, Saab has issued Revision 1 of Service Bulletin 340-32-094, dated March 4, 1994. This revised service bulletin is essentially identical to the originally released version, which was referenced in the notice, but contains certain clarifications, revised illustrations, and provisions for use of an alternative washer. The Luftfartsverket, which is the airworthiness authority for Sweden, has approved the technical content of this revised service bulletin. The FAA has revised the final rule to include reference to the revised service bulletin as an additional source of appropriate service information.

This same commenter requests clarification as to whether or not the proposed rule would require replacement of corroded bolts if any were found during the magnaflux inspection that would be required by paragraph (b)(1) of the proposal. The FAA notes that the Saab Service Bulletin 340-32-094, which is referenced in the notice, mentions hydrogen embrittlement (corrosion) as one of the reasons for fractures of the subject retaining bolts; however, that service bulletin does not directly address corrosion in its instructions for inspection. That service bulletin does contain attachments comprised of several AP Precision Hydraulic, Ltd., service bulletins, however, and several of those service bulletins do contain instructions for visually inspecting the retainer bolts for corrosion, cracking, or damage, and removing any bolt that exhibits such discrepancies. Further, the FAA points out that, under normal maintenance practices, these bolts are inspected visually to detect cracks, corrosion, or other damage whenever they are removed, and are replaced if discrepancies exist. Since the bolts must be removed for the visual and magnaflux inspections required by paragraph (b)(1) of the rule, they would necessarily be inspected for corrosion at that time if normal maintenance practices are followed. The FAA has added "NOTE 1" to paragraph (b)(1) of the final rule to remind operators of the need to visually inspect the bolts for corrosion and to replace any corroded bolts.

After careful review of the available data, including the comment noted above, the FAA has determined that air safety and the public interest require the adoption of the rule with the changes previously described. The FAA has determined that these changes will neither increase the economic burden on any operator nor increase the scope of the AD.

The FAA estimates that 217 airplanes of U.S. registry will be affected by this AD, that it will take approximately 4 workhours per airplane to accomplish the required actions, and that the average labor rate is $55 per work hour. Required parts will be provided at no cost to operators. Based on these figures, the total cost impact of the AD on U.S. operators is estimated to be $47,740, or $220 per airplane.

The total 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.

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. App. 1354(a), 1421 and 1423; 49 U.S.C. 106(g); and 14 CFR 11.89.

39.13 - [Amended]
2. Section 39.13 is amended by adding the following new airworthiness directive: