AD 94-26-14

This amendment adopts a new airworthiness directive (AD), applicable to all British Aerospace Model Viscount 744, 745D, and 810 series airplanes, that requires inspections to detect cracks in the chassis side bracing structure and in the chassis top strut support intercostals inside the wings, and replacement of discrepant parts with new parts. This proposal would also require inspection of the intercostals to determine the specification of the material, if necessary; and replacement of discrepant parts with new parts. This amendment is prompted by a report of cracking in the chassis top strut support intercostal in the side bracing structure inside the wing due to the effects of metal fatigue. The actions specified by this AD are intended to prevent such fatigue-related cracking, which could lead to the failure of the chassis side bracing structure inside the wings and consequent reduced structural integrity of the chassis support structure.

Final rule

94-26-14 BRITISH AEROSPACE REGIONAL AIRCRAFT LIMITED (FORMERLY BRITISH AEROSPACE COMMERCIAL AIRCRAFT LIMITED, VICKERS-ARMSTRONGS AIRCRAFT LIMITED): Amendment 39-9109. Docket 94-NM-108-AD.
Applicability: All Model Viscount 744, 745D, and 810 series airplanes, certificated in any category.

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 use the authority provided in paragraph (b) to request approval from the FAA. This approval may address either no action, if the current configuration eliminates the unsafe condition; or different actions necessary to address the unsafe condition described in this AD. Such a request should include an assessment of the effect of the changed configuration on the unsafe condition addressed by this AD. In no case does the presence of any modification, alteration, or repair remove any airplane from the applicability of this AD.

Compliance: Required as indicated, unless accomplished previously.

To prevent reduced structural integrity of the chassis, accomplish the following:

(a) Within 6 months after the effective date of this AD, perform a detailed visual inspection to detect cracks in the chassis side bracing structure and in the chassis top strut support intercostals inside the wings between stations 81 and 96, in accordance with British Aerospace Viscount Preliminary Technical Leaflet (PTL) 332, Issue 1, Disc 11 Doc.4, dated December 2, 1991 (for Model Viscount 744 and 745D series airplanes); or British Aerospace Viscount PTL 203, Issue 1, Disc 11 Doc.2, dated December 2, 1991 (for Model Viscount 810 series airplanes); as applicable.

(1) If no cracking is detected in the chassis side bracing structure, repeat the inspection thereafter at intervals not to exceed 1,500 flight hours or 14 months, whichever occurs first.

(2) If any cracking is detected in the chassis side bracing structure, prior to further flight, replace the cracked side of the bracing structure with a new structure, in accordance with the applicable PTL.

(3) If no cracking is detected in the chassis top strut support intercostal, prior to further flight, perform an eddy current inspection to determine the specification of the material (either L72 or L73) of the intercostals, in accordance with the applicable PTL.

(i) If the material is manufactured from L72, prior to further flight, replace the chassis top strut support intercostal with a new chassis top strut support intercostal, in accordance with the applicable PTL.

(ii) If the material is manufactured from L73, no further action is required by paragraph (a)(3) of this AD.

(4) If cracking is detected in the chassis top strut support intercostal, prior to further flight, replace it with a new chassis top strut support intercostal, in accordance with the applicable PTL.

(b) 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 Standardization Branch, ANM-113.

(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 AD can be accomplished.

(d) The inspections and replacements shall be done in accordance with British Aerospace Viscount Preliminary Technical Leaflet (PTL) 332, Issue 1, Disc 11 Doc.4, dated December 2, 1991 (for Model Viscount 744 and 745D series airplanes); or British Aerospace Viscount PTL 203, Issue 1, Disc 11 Doc.2, dated December 2, 1991 (for Model Viscount 810 series airplanes); as applicable. 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 Ltd., Engineering Support Manager, Military Business Unit, Chadderton Works, Greengate, Middleton, Manchester M24 1SA, England. 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.

(e) This amendment becomes effective on February 3, 1995.

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 Model Viscount 744, 745D, and 810 series airplanes was published in the Federal Register on September 9, 1994 (59 FR 46596). That action proposed to require repetitive detailed visual inspections to detect cracks in the chassis side bracing structure and in the chassis top strut support intercostals of the inner wings, and replacement of discrepant parts with new parts. That action also proposed to require an eddy current inspection to determine the specification of the material of the intercostals, if necessary; and replacement of discrepant parts with new parts.

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

The commenter supports the proposed rule.

As aresult of recent communications with the Air Transport Association (ATA) of America, the FAA has learned that, in general, some operators may misunderstand the legal effect of AD's on airplanes that are identified in the applicability provision of the AD, but that have been altered or repaired in the area addressed by the AD. The FAA points out that all airplanes identified in the applicability provision of an AD are legally subject to the AD. If an airplane has been altered or repaired in the affected area in such a way as to affect compliance with the AD, the owner or operator is required to obtain FAA approval for an alternative method of compliance with the AD, in accordance with the paragraph of each AD that provides for such approvals. A note has been added to this final rule to clarify this requirement.

The FAA has recently reviewed the figures it has used over the past several years in calculating the economic impact of AD activity. In order to account for various inflationary costs in the airline industry, the FAA has determined that it is necessary to increase the labor rate used in these calculations from $55 per work hour to $60 per work hour. The economic impact information, below, has been revised to reflect this increase in the specified hourly labor rate.

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 25 Model Viscount 744 and 745D series airplanes of U.S. registry will be affected by this AD, that it will take approximately 15 work hours per airplane to accomplish the required actions, and that the average labor rate is $60 per work hour. Based on these figures, the total cost impact of the AD on U.S. operators is estimated to be $22,500, or $900 per airplane, per inspection cycle.

The FAA estimates that 4 Model Viscount 810 series airplanes of U.S. registry will be affected by this AD, that it will take approximately 15 work hours per airplane to accomplish the required actions, and that the average labor rate is $60 per work hour. Based on these figures, the total cost impact of the proposed AD on U.S. operators is estimated to be $3,600, or $900 per airplane, per inspection cycle.

Based on the above figures, the total cost impact of the actions proposed by this AD on U.S. operators is estimated to be $26,100, or $900 per airplane, per inspection cycle.

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 onthe 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."

Listof 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: