01-25696. Airworthiness Directives; Sikorsky Aircraft Corporation Model S-76A Helicopter

AGENCY:

Federal Aviation Administration, DOT.

ACTION:

Notice of proposed rulemaking (NPRM).

SUMMARY:

This document proposes superseding an existing airworthiness directive (AD) for Sikorsky Aircraft Corporation (Sikorsky) Model S-76A helicopters. That AD currently requires a service life limit on certain landing gear parts based on hours time-in-service (TIS). This action would add another method of calculating the life limit for certain landing gear parts based on cycles and would require the operator to choose and record the method of calculating the service life of each part in the rotorcraft history or equivalent record. This action would also require replacing the part based upon either the maximum hours TIS or the maximum cycles but not both. This proposal is prompted by the need to add flight cycles as a method of calculating the life limit for certain landing gear parts based on fatigue analyses. The actions required by the proposed AD are intended to add or revise the retirement life for certain landing gear parts to prevent fatigue failure of the landing gear and subsequent loss of control of the helicopter.

DATES:

Comments must be received on or before December 11, 2001.

ADDRESSES:

Submit comments in triplicate to the Federal Aviation Administration (FAA), Office of the Regional Counsel, Southwest Region, Attention: Rules Docket No. 2000-SW-46-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]. Comments may be inspected at the Office of the Regional Counsel between 9 a.m. and 3 p.m., Monday through Friday, except Federal holidays.

FOR FURTHER INFORMATION CONTACT:

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

SUPPLEMENTARY INFORMATION:

Comments Invited

Interested persons are invited to participate in the making of the proposed 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 above. All communications received on or before the closing date for comments will be considered before taking action on the proposed rule. The proposals contained in this document may be changed in light of the comments received.

Comments are specifically invited on the overall regulatory, economic, environmental, and energy aspects of the proposed rule. All comments submitted will be available in the Rules Docket for examination by interested persons. A report summarizing each FAA-public contact concerned with the substance of this proposal will be filed in the Rules Docket.

Commenters wishing the FAA to acknowledge receipt of their mailed comments submitted in response to this proposal must submit a self-addressed, stamped postcard on which the following statement is made: “Comments to Docket No. 2000-SW-46-AD.” The postcard will be date stamped and returned to the commenter.

Availability of NPRMs

Any person may obtain a copy of this NPRM by submitting a request to the FAA, Office of the Regional Counsel, Southwest Region, Attention: Rules Docket No. 2000-SW-46-AD, 2601 Meacham Blvd., Room 663, Fort Worth, Texas 76137.

Discussion

On April 23, 1986, the FAA issued AD 86-09-11, Amendment 39-5298 (51 FR 17009, May 8, 1986), to require placing a service life limit on certain landing gear parts on Sikorsky Model S-76A helicopters based on hours TIS. That action was prompted by safety considerations and landing gear fatigue analysis. The requirements of that AD are intended to prevent fatigue failure of landing gear parts and landing gear.

Since the issuance of that AD, Sikorsky has issued a revision and a Supplement No.1 to the Airworthiness Limitations Section, Chapter 4, of the Sikorsky Maintenance Manual SA 4047-76-2-1. Replacing the parts in accordance with the revisions dated May 9, 1997 (page 1), and March 2, 1999 (page 2), constitutes compliance with this AD when applied to helicopters that have not been modified by Supplemental Type Certificate (STC) SH568NE. Replacing the parts in accordance with Supplement No. 1, dated May 21, 1997, revised pages 2 and 3 dated March 2, 1999, constitutes compliance with this AD when applied to helicopters that have been modified by STC SH568NE. The change and supplement specify replacing parts installed in the Sikorsky Model S-76A helicopter at the expiration of a specified number of cycles.

The life limit in AD 86-09-11 is based on hours TIS, and the life limit in the airworthiness limitations section of the maintenance manual is based on cycles. The proposed AD would supersede AD 86-09-11, retaining a life limit based on hours TIS but also allowing the life limit to be based on cycles for certain landing gear parts. The proposed AD would also require recording the method selected for calculating the life limit of the landing gear parts in the rotorcraft history or equivalent records and using only that method throughout the life of the part. A cycle is defined as one takeoff to a hover or other mode of flight and one landing.

The FAA estimates that 87 helicopters of U.S. registry would be affected by this proposed AD, that it would take approximately 2 work hours per helicopter to determine the number of cycles, 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 $10,440.

The regulations proposed herein would 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 proposal would not have federalism implications under Executive Order 13132.

For the reasons discussed above, I certify that this proposed regulation (1) is not a “significant regulatory action” under Executive Order 12866; (2) is not a “significant rule” under the DOT Regulatory Policies and Procedures (44 FR 11034, February 26, 1979); and (3) if promulgated, 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 copy of the draft regulatory evaluation prepared for this action is contained in the Rules Docket. A copy of it may be obtained by contacting 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

The Proposed Amendment

Accordingly, pursuant to the authority delegated to me by the Administrator, the Federal Aviation Administration proposes to amend 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 removing Amendment 39-5298 (51 FR 17009, May 8, 1986), and by adding a new airworthiness directive (AD), to read as follows:

Sikorsky Aircraft Corporation: Docket No. 2000-SW-46-AD. Supersedes AD 86-09-11, Amendment 39-5298, Docket No. 86-ASW-12.

Applicability: Model S-76A helicopters, 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 (e) 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 as indicated, unless accomplished previously.

To prevent fatigue failures of the main and nose landing gear parts and subsequent loss of control of the helicopter, accomplish the following:

(a) Within 50 hours time-in-service (TIS), determine either the hours TIS or cycles accumulated on each part listed in Table 1 or Table 2 of this AD, as applicable. A cycle is a takeoff to a hover or other mode of flight and a landing.

(1) If neither the hours TIS nor cycles are known for an affected part, assume the rotorcraft's total hours TIS are the hours TIS for that part.

(2) If only one history is known for the part (either hours TIS or cycles), use that method for tracking the remaining life of that part.

(3) Thereafter, record in the rotorcraft history or equivalent record the selected method of calculating the life limit for each landing gear part, and record either the accumulated hours TIS or cycles for the selected method.

(b) Before further flight, remove from service each part listed in the following Table 1 of this AD on or before reaching the applicable life limit:

Table 1

Component	Part No.	Life limit hours TIS	Life limit cycles
(1) Main Landing Gear:
(i) Cylinder	1945E2	30,300	136,350
(ii) Axle Support Fitting	1945C12	9,600	43,200
(iii) Pin, Universal to Cylinder	1945C29	23,800	107,100
(iv) Drag Brace Rod End	1945E35	38,200	171,900
(v) Upper Torque Arm	1945E46	37,900	170,550
(vi) Lower Torque Arm	1945C47	16,200	72,900
(vii) Axle	195E85	23,380	105,210
(viii) Rod End, Positioning Rod	1945E235	19,100	85,950
(ix) Retraction Actuator:
(A) Outer Cylinder	1945E302, 1945F302	7,100	31,950
(B) Piston	1945E314	33,300	148,500
(C) Piston Rod End	01-747-061	8,000	36,000
(2) Nose Landing Gear:
(i) Fork	1944E60	42,500	191,250
(ii) Cylinder	1944C2, 1944E2	18,500	83,250
(iii) Drag Brace Actuator:
(A) Cylinder Terminal	1944D201	28,800	129,600
(B) Piston Rod	1944E204	22,000	99,000

(c) For helicopters modified by Supplemental Type Certificate (STC) SH568NE, before further flight, remove from service each part listed in the following Table 2 of this AD on or before reaching the applicable life limit:

Table 2

Component	Part No.	Life limit hours TIS	Life limit cycles
(1) Main Landing Gear:
(i) Cylinder	1945E2, 2071-2	24,000	108,000
(ii) Piston	1945E4, 2071-4	28,600	128,700
(iii) Axle Support Fitting	1945C12, 2071-12	7,400	33,300
(iv) Pin, Universal to Cylinder	1945C29, 2071-29	16,000	72,000
(v) Pin, Positioning Rod to Upper Torque Arm	1945A32, 2071-32	25,000	112,500
(vi) Drag Brace Rod End	1945E35, 2071-35	23,864	107,388
(vii) Upper Torque Arm	1945E46, 2071-46	26,829	120,730
(viii) Lower Torque Arm	1945C47, 2071-47	11,928	53,676
(ix) Lower Drag Brace	1945E74, 2071-74	46,000	207,000
(x) Retraction Brace	1945E76A11, 1945E76A12, 2071-76-11, 2071-76-12	41,000	184,500
(xi) Axle	1945E85, 2071-85	23,380	105,210
(xii) Rod End, Positioning Rod	1945E235, 2071-235	13,600	61,200
(xiii) Retraction Actuator:
(A) Outer Cylinder	1945E302, 1945F302	7,100	31,950
(B) Piston	1945E314	33,000	148,500
(C) Piston Rod End	01-747-061	8,000	36,000
(2) Nose Landing Gear:
(i) Axle	1944B85, 2070-85	49,833	224,248
(ii) Fork	1944E60, 2070-60	32,000	144,000
(iii) Piston	1944E4, 2070-4	35,878	161,451
(iv) Cylinder	1944C2, 1944E2, 2070-2	13,500	60,750
(v) Drag Brace Actuator:
(A) Cylinder Terminal	1944D201, 2070-201	23,000	103,500
(B) Piston Terminal	1944E212B, 2070-212	40,000	180,000
(C) Piston Rod	1944E204	22,000	99,000

(d) This AD revises the Limitations section of the maintenance manual by establishing or revising the retirement lives for the affected parts shown in Tables 1 and 2 of this AD and establishing cycle counting as an additional method to determine retirement for the affected parts. Installing STC SH568NE affects the retirement life of certain parts.

(e) 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 Maintenance Inspector, who may concur or comment and then send it to the Manager, Boston Aircraft Certification Office.

Note 2:

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

(f) 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.

Issued in Fort Worth, Texas, on October 3, 2001.

Mark R. Schilling,

Acting Manager, Rotorcraft Directorate, Aircraft Certification Service.