AD 94-26-16

This amendment adopts a new airworthiness directive (AD), applicable to all British Aerospace Model Viscount 744, 745D, and 810 series airplanes, that requires various inspections to detect damage, corrosion, or cracking of certain taper plugs and split bushings of the engine mount, and replacement of taper plugs or split bushings with serviceable parts, if necessary. This amendment is prompted by a report of damage of the taper plug and split bushing of the engine mount due to the effects of corrosion. The actions specified by this AD are intended to prevent such damage, which could lead to failure of the engine mount attachment assembly and consequent separation of the engine from the airplane.

Final rule

94-26-16 BRITISH AEROSPACE REGIONAL AIRCRAFT LIMITED (FORMERLY BRITISH AEROSPACE COMMERCIAL AIRCRAFT LIMITED, VICKERS-ARMSTRONGS AIRCRAFT LIMITED): Amendment 39-9111. Docket 94-NM-104-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 (c) 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 separation of the engine from the airplane, accomplish the following:

(a) At the next unscheduled engine removal, but no later than 12 months after the effective date of this AD, perform a detailed visual inspection to detect damage, corrosion, or cracking of taper plugs, having part number (P/N) 60216-1017, and split bushings (bushes), having P/N 60216-1019, of the engine mount, in accordance with British Aerospace Viscount Preliminary Technical Leaflet (PTL) 200, Disc 9 Doc.5, dated December 6, 1991 (for Model Viscount 810 series airplanes); or British Aerospace Viscount PTL 329, Disc. 9 Doc.2, dated April 1, 1992 (for Model Viscount 744 and 745D series airplanes); as applicable.

(1) If notaper plugs or split bushings are damaged, corroded, or cracked, repeat the inspection thereafter at each unscheduled engine removal, but no later than 48 months after the last visual inspection of the taper plugs and split bushings.

(2) If any taper plug or split bushing is damaged, corroded, or cracked, prior to further flight, replace the taper plug or split bushing with a serviceable part, in accordance with the applicable PTL. Thereafter, repeat the inspection at each unscheduled engine removal, but no later than 48 months after the last visual inspection of the taper plugs and split bushings.

(b) At the next scheduled engine removal, but no later than 12 months after the effective date of this AD, perform detailed visual and nondestructive test (NDT) inspections to detect damage, corrosion, or cracking of all taper plugs and split bushings of the engine mount, in accordance with British Aerospace Viscount PTL 200, Disc 9 Doc.5, dated December 6, 1991 (for Model Viscount 810 series airplanes); or British Aerospace Viscount PTL 329, Disc. 9 Doc.2, dated April 1, 1992 (for Model Viscount 744 and 745D series airplanes); as applicable.

(1) If no taper plug or split bushing is damaged, corroded, or cracked, repeat the visual and NDT inspections thereafter at each scheduled engine removal, but no later than 48 months after the last visual and NDT inspections of the taper plugs and split bushings.

(2) If any taper plug or split bushing is damaged, corroded, or cracked, prior to further flight, replace the taper plug or split bushing with a serviceable part, in accordance with the applicable PTL. Thereafter, repeat the visual and NDT inspections at each scheduled engine removal, but no later than 48 months after the last visual and NDT inspections of the taper plugs and split bushings.

(c) 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.

(d) 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.

(e) The inspections and replacements shall be done in accordance with British Aerospace Viscount Preliminary Technical Leaflet (PTL) 200, Disc 9 Doc.5, dated December 6, 1991 (for Model Viscount 810 series airplanes); or British Aerospace Viscount PTL 329, Disc.9 Doc.2, dated April 1, 1992 (for Model Viscount 744 and 745D 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.

(f) This amendment becomes effective on March 1, 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 14, 1994 (59 FR 47101). That action proposed to require detailed visual and nondestructive test (NDT) inspections to detect damage, corrosion, or cracking of certain taper plugs and split bushings of the engine mount, and replacement of discrepant 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 a result 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 25 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 of these airplanes is estimated to be $37,500, or $1,500 per airplane.

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 25 work hours per airplane to accomplish the proposed 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 of these airplanes is estimated to be $6,000, or $1,500 per airplane.

Based on the above figures, the total cost impact of the actions proposed by this AD on U.S. operators is estimated to be $43,500, or $1,500 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: