AD 97-19-10

This amendment supersedes an existing airworthiness directive (AD), applicable to Sikorsky Aircraft-manufactured Model S-64E and S-64F helicopters, that currently requires initial and repetitive inspections of the main gearbox assembly second stage lower planetary plate (plate) for cracks, and removal and replacement of the plate if cracks are found; and daily inspections of certain main transmission oil filter packs for magnesium chips, and removal and replacement of the main transmission if chips are found. The AD also provides for reworking and re-identifying the plate, as well as establishes a retirement life for the plate, including those that have been reworked and re-identified. This amendment requires, for Model S-64E helicopters, inspections and rework of the plate and establishes a new retirement life for the plate. This amendment is prompted by the type certificate holder's reports that four plates were discovered to have cracks, three of which had been reworkedin accordance with the existing AD. The actions specified by this AD are intended to add another plate to the applicability of the AD, remove the requirements of AD 77-20-01 for the Model S-64F and prevent failure of the plate on the Model S-64E due to fatigue cracking, which could lead to failure of the main gearbox and subsequent loss of control of the helicopter.

Final rule

97-19-10 ERICKSON AIR-CRANE CO.: Amendment 39-10130. Docket No. 96-SW-04-AD. Supersedes AD 77-20-01, Amendment 39-3045 and Amendment 39-3064.

Applicability: Sikorsky Aircraft-manufactured Model S-64E helicopters, with main gearbox assembly second stage lower planetary plate (plate), part number (P/N) 6435-20229-102, reidentified as P/N 6435-20229-102-TS-107 after rework, or P/N 6435-20229-104, installed, certificated in any category.

NOTE 1: This AD applies to each helicopter 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 helicopters 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 (d) 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 helicopter from the applicability of this AD.

Compliance: Required as indicated, unless accomplished previously.

To prevent failure of the plate due to fatigue cracking, which could lead to failure of the main gearbox and subsequent loss of control of the helicopter, accomplish the following:

(a) For plate, part number (P/N) 6435-20229-102 and P/N 6435-20229-102-TS-107, at 1,300 hours total time-in-service (TIS), inspect and rework or replace the plate, as appropriate, in accordance with the Accomplishment Instructions, paragraph 2A., steps (1), and (3) through (11), of Erickson Air Crane Co. Service Bulletin No. 64B35-7C, dated November 8, 1995.

(b) For any plate, P/N 6435-20229-102, that has been reworked and identified with "TS- 107", and for plate, P/N 6435-20229-104, at 1,500 hours TIS and thereafter at intervals not to exceed 70 hours TIS, inspect the plate in accordance with the Accomplishment Instructions, paragraph 2B., step (1), of Erickson Air-Crane Co. Service Bulletin No. 64B35-7C, dated November 8, 1995. If a crack is found, replace the main gearbox assembly with an airworthy assembly.

(c) This AD revises the airworthiness limitation section of the maintenance manual by establishing a retirement life of 2,600 hours TIS for the main gearbox assembly second stage planetary plate, P/N 6435-20229-102, reidentified as P/N 6435-20229-102-TS-107 after rework, and P/N 6435-20229-104.

(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, Rotorcraft Certification Office, Rotorcraft Directorate, FAA. Operators shall submit their requests through an FAA Principal Maintenance Inspector, who may concur or comment and then send it to the Manager, Rotorcraft Certification Office.

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

(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 helicopter to a location where the requirements of this AD can be accomplished.

(f) The inspections and rework or replacement, as necessary, shall be done in accordance with Erickson Air Crane Co. Service Bulletin No. 64B35-7C, dated November 8, 1995. 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 Erickson Air-Crane Co., 3100 Willow Springs Rd., P.O. Box 3247, Central Point, OR 97502. Copies may be inspected at the FAA, Office of the Assistant Chief Counsel, 2601 Meacham Blvd., Room 663, Fort Worth, Texas; or at the Office of the Federal Register, 800 North Capitol Street, NW., suite 700, Washington, DC.

(g) This amendment becomes effective on October 17, 1997.

A proposal to amend part 39 of the Federal Aviation Regulations (14 CFR part 39) by superseding AD 77-20-01, Amendment 39-3045 (42 FR 51565, September 29, 1977), which was revised by Amendment 39-3064 (42 FR 56600, October 27, 1977), and is applicable to Sikorsky Aircraft-manufactured Model S-64E and S-64F helicopters, was published in the Federal Register on October 11, 1996 (61 FR 53339). That action proposed to require, at 1,300 hours time-in-service (TIS), a fluorescent magnetic particle inspection of the plate, part number (P/N) 6435-20229-102, for cracks, replacement of the plate if a crack is found, and reworking the plate if no crack is found. The action also proposed to require, at 1,500 hours TIS, and thereafter at intervals not to exceed 70 hours TIS, for reworked plate, P/N 6435-20229-102, reidentified as P/N 6435-20229-102-TS-107 after rework, and for plate, P/N 6435-20229-104, a borescope inspection for cracks and replacement of the plate if a crack is found. Finally, it was proposed that these part- numbered plates be retired upon reaching 2,600 hours TIS.

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 states that the AD should not be applicable to Model S64F helicopters as in the existing AD because of differences in part numbers between that model helicopter and the Model S64E helicopter. The FAA concurs, and did not include Model S64F helicopters in the applicability portion of the proposal, nor in this final rule.

A second commenter addressed restricted category Model CH54A helicopters. This AD does not affect those model helicopters--only Model S64E helicopters. The FAA anticipates issuing another AD applicable to Model CH54A helicopters at a later date.

After careful review of the available data, including the comments previously noted, the FAA has determined thatair safety and the public interest require the adoption of the rule as proposed except for adding "reidentified as" prior to P/N 6435-20229-102-TS-107, and "after rework" after that P/N. The FAA has determined that these non-substantive changes will neither increase the economic burden on any operator nor increase the scope of the AD.

The FAA estimates that 8 helicopters of U.S. registry will be affected by this AD, that it will take approximately 8 work hours per helicopter to accomplish the inspections and 56 hours to remove and replace the main gearbox assembly, if necessary, and that the average labor rate is $60 per work hour. Required parts will cost $8,000 per helicopter. Based on these figures, the total cost impact of this AD on U.S. operators is estimated to be $94,720; $3,840 to accomplish the inspections, and $90,880 to replace the plate in the main gearbox assembly in all 8 helicopters, if necessary.

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 USC 106(g), 40113, 44701.

39.13 - [Amended]
2. Section 39.13 is amended by removing Amendment 39-3045 (42 FR 51565, September 29, 1977) and 39-3064 (42 FR 56600, October 27, 1977), and by adding a new airworthiness directive (AD), Amendment 39-10130, to read as follows: