01-31041. Airworthiness Directives; Sikorsky Model S-70A and S-70C Helicopters

AGENCY:

Federal Aviation Administration, DOT.

ACTION:

Final rule; request for comments.

SUMMARY:

This amendment adopts a new airworthiness directive (AD) for Sikorsky Model S-70A and S-70C helicopters. This action requires certain inspections of each main landing gear drag beam (beam) for a crack and removing any cracked beam before further flight. This action also requires reducing the torque of the jackpad mounting bolt retention nut (nut) of each beam. This amendment is prompted by failure of a beam due to stress corrosion resulting from sustained tensile stress due partly to excessive torque of the nut. The actions specified in this AD are intended to prevent excessive torque of the nut, failure of a beam, and subsequent loss of control of the helicopter during takeoff or landing.

DATES:

Effective January 2, 2002.

Comments for inclusion in the Rules Docket must be received on or before February 19, 2002.

ADDRESSES:

Submit comments in triplicate to the Federal Aviation Administration (FAA), Office of the Regional Counsel, Southwest Region, Attention: Rules Docket No. 2001-SW-18-AD, 2601 Meacham Blvd., Room 663, Fort Worth, Texas 76137. You may also send comments electronically to the Rules Docket at the following address: [e-mail].

FOR FURTHER INFORMATION CONTACT:

Terry Fahr, Aviation Safety Engineer, Boston Aircraft Certification Office, 12 New England Executive Park, Burlington, MA 01803, telephone [phone], fax [phone].

SUPPLEMENTARY INFORMATION:

This amendment adopts a new AD for Sikorsky Model S-70A and S-70C helicopters. This action requires certain inspections of each beam for a crack and removing any cracked beam before further flight. This AD also requires reducing the torque of the nut on each beam. This amendment is prompted by the failure of a beam due to stress corrosion resulting from sustained tensile stress due partly to excessive torque on the nut.

The FAA has reviewed Sikorsky Alert Service Bulletin No. 70-03-2, dated July 26, 1999 (ASB). The ASB describes procedures for reducing the torque on each nut to 45-50 ft-lbs to reduce stress to the beam.

We have identified an unsafe condition that is likely to exist or develop on other Sikorsky Model S-70A and S-70C helicopters of the same type designs. Therefore, this AD is being issued to prevent excessive torque on a nut, failure of a beam, and subsequent loss of control of the helicopter during takeoff or landing. The short compliance time involved is required because the previously described critical unsafe condition can adversely affect the controllability and structural integrity of the helicopter. Therefore, within 30 hours time-in-service, the following actions are required for the beam, and this AD must be issued immediately:

• Visually inspect each beam for a crack.
• If a crack is found, remove the beam before further flight.
• If a crack is suspected, dye-penetrant inspect the beam, and if a crack is found, remove the beam before further flight.
• If no crack is found, reduce the torque on the nut.

Since a situation exists that requires the immediate adoption of this regulation, it is found that notice and opportunity for prior public comment hereon are impracticable, and that good cause exists for making this amendment effective in less than 30 days.

The FAA estimates that 3 helicopters on the U.S. register will be affected by this AD, that it will take approximately 2 work hours to inspect the beam and to reduce the torque on each nut, and 2 work hours to replace a cracked beam. The average labor rate is $60 per work hour. Required parts will cost approximately $18,600 per beam. Based on these figures, the total cost impact of the AD on U.S. operators is estimated to be $56,520, assuming one beam has to be replaced on each affected helicopter.

Comments Invited

Although this action is in the form of a final rule that involves requirements affecting flight safety and, thus, was not preceded by notice and an opportunity for public comment, comments are invited on this rule. Interested persons are invited to comment on this rule by submitting such written data, views, or arguments as they may desire. Communications should identify the Rules Docket number and be submitted in triplicate to the address specified under the caption ADDRESSES. All communications received on or before the closing date for comments will be considered, and this rule may be amended in light of the comments received. Factual information that supports the commenter's ideas and suggestions is extremely helpful in evaluating the effectiveness of the AD action and determining whether additional rulemaking action would be needed.

Comments are specifically invited on the overall regulatory, economic, environmental, and energy aspects of the rule that might suggest a need to modify the rule. All comments submitted will be available in the Rules Docket for examination by interested persons. A report that summarizes each FAA-public contact concerned with the substance of this AD will be filed in the Rules Docket.

Commenters wishing the FAA to acknowledge receipt of their mailed comments submitted in response to this rule must submit a self-addressed, stamped postcard on which the following statement is made: “Comments to Docket No. 2001-SW-18-AD.” The postcard will be date stamped and returned to the commenter.

The regulations adopted herein will not have a substantial direct effect 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, it is determined that this final rule does not have federalism implications under Executive Order 13132.

The FAA has determined that this regulation is an emergency regulation that must be issued immediately to correct an unsafe condition in aircraft, and that it is not a “significant regulatory action” under Executive Order 12866. It has been determined further that this action involves an emergency regulation under DOT Regulatory Policies and Procedures (44 FR 11034, February 26, 1979). If it is determined that this emergency regulation otherwise would be significant under DOT Regulatory Policies and Procedures, a final regulatory evaluation will be prepared and placed in the Rules Docket. A copy of it, if filed, 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
• 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. 106(g), 40113, 44701.

§ 39.13

[Amended]

2. Section 39.13 is amended by adding a new airworthiness directive to read as follows:

2001-25-08 Sikorsky Aircraft Corporation: Amendment 39-12561. Docket No. 2001-SW-18-AD.

Applicability: Model S-70A helicopters, serial numbers 700029, 701129, 701322, 701325, 701327, 701329, 701331, 701333, 701592, 701593,701594, 701595, 701613, 701614, 701825, 701835, 702127, and 702129, and Model S-70C helicopters, serial numbers 70583, 70785, 70788, 70792, 70793, 70794, 70797, 70798, 70799, 70800, 70811, 70812, 70813, 70830, 70831, 70836, 70837, 70848, 70855, 70856, 70867, 70868, 70879, 70884, 70892, 70910, 70918, 70927, 70928, 70929, 70949, 70950, 70951, 70954, 70957, 70958, 70959, 70965, 70966, and 701029, certificated in any category.

Note 1:

This AD applies to each helicopter identified in the preceding applicability provision, regardless of whether it has been otherwise 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 request approval for an alternative method of compliance in accordance with paragraph (c) 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.

Compliance: Required within 30 hours time-in-service, unless accomplished previously.

To prevent excessive torque on a jackpad mounting bolt retention nut (nut), failure of a main landing gear drag beam (beam), and subsequent loss of control of the helicopter during takeoff or landing, accomplish the following:

(a) With jackpad installed, using a 10X or higher magnifying glass, visually inspect each beam, part number (P/N) 70250-32105, for a crack at a 3.0-inch radius around the upper and lower jackpad holes.

(1) If a crack is found, remove the beam.

(2) If a crack is suspected, dye-penetrant inspect the beam, and if a crack is found, remove the beam.

Note 2:

Temporary Revision No. 19 of Sikorsky Aircraft Model S-70 Maintenance Manual, dated January 23, 2001, pertains to the subject of this AD.

(b) If a crack is not found while accomplishing the requirements of paragraph (a) of this AD, retorque the nut, part number (P/N) MS21245-L12, on each beam as follows:

(1) Restrain the jackpad and rotate the nut counterclockwise to release the torque on the nut. If movement of the jackpad occurs, remove and replace the sealant from the lower surface of the jackpad/beam interface.

(2) Retorque the nut to 45-50 ft-lbs.

(3) Apply sealant to the nut and the immediate area.

(4) After sealant has dried, touch up the paint as required.

(5) After the paint has dried, apply a slippage mark (of a contrasting color) to the nut as follows:

(i) Wipe the area to be marked with a clean-lint-free cloth.

(ii) Apply F1000 Sentry Seal, or equivalent, with a width of approximately one half the diameter of the nut (to a maximum width of 3/16 inch) and extending a minimum of 1/2 inch on the base part (or to the edge of the part, whichever is smaller).

Note 3:

Sikorsky Alert Service Bulletin No. 70-03-2, dated July 26, 1999, pertains to the subject of this AD.

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

Note 4:

Information concerning the existence of approved alternative methods of compliance with this AD, if any, may be obtained from the Boston Aircraft Certification Office.

(d) Special flight permits may be issued in accordance with 14 CFR 21.197 and 21.199 to operate the helicopter to a location where the requirements of this AD can be accomplished.

(e) This amendment becomes effective on January 2, 2002.

Issued in Fort Worth, Texas, on December 11, 2001.

David A. Downey,

Manager, Rotorcraft Directorate, Aircraft Certification Service.