AD 97-05-06

This amendment supersedes an existing airworthiness directive (AD), applicable to Schweizer Aircraft Corporation and Hughes Helicopters, Inc. Model 269A, 269A-1, 269A-2, and 269B helicopters, that currently requires initial and repetitive inspections of the main rotor thrust bearing (bearing) for bearing rotational roughness, corrosion, inadequate lubrication, physical damage, or excessive zinc chromate paste or moisture. This amendment requires the same initial and repetitive inspections required by the existing AD, but would extend the retirement life for certain bearings, and would remove the Model 269A-2 helicopter from, and add the Model TH-55A helicopters to the applicability of this AD. This amendment is prompted by an FAA analysis of service information issued by the manufacturer that extends the retirement life for certain bearings. The actions specified by this AD are intended to prevent failure of the bearing, loss of the main rotor, and subsequent loss of control of the helicopter.

Final rule

97-05-06 SCHWEIZER AIRCRAFT CORPORATION AND HUGHES HELICOPTERS, INC.: Amendment 39-9950. Docket No. 94-SW-17-AD. Supersedes AD 68-21-05, Amendment 39-1055 and Amendment 39-672.

Applicability: Model 269A helicopters, serial numbers (S/N) 0011 through 1109, Model 269A-1 helicopters, S/N 0001 through 0041, Model 269B, S/N 0001 through 0444, and Model TH-55A, with main rotor thrust bearing, part number (P/N) 269A5050-50, -51, or -73, 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 (g) 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 within 25 hours time-in-service (TIS) after the effective date of this AD, unless accomplished previously.

To prevent failure of the main rotor thrust bearing (bearing), loss of the main rotor, and subsequent loss of control of the helicopter, accomplish the following:

(a) From available helicopter records, determine the TIS of the appropriate bearing, part number (P/N) 269A5050-50, P/N 269A5050-51, or P/N 269A5050-73.

(1) If the TIS on the bearing, P/N 269A5050-50 or -51, equals or exceeds 300 hours TIS, replace the bearing with an airworthy bearing beforefurther flight.

(2) If the TIS on the bearing, P/N 269A5050-50 or -51, equals or exceeds 275 hours TIS, and is less than 300 hours TIS, replace the bearing with an airworthy bearing within the next 25 hours TIS.

(3) If the TIS on the bearing, P/N 269A5050-50 or -51, is less than 275 hours TIS, replace the bearing with an airworthy bearing on or before 300 hours TIS.

(b) Inspect bearing, P/N 269A5050-50 or -51, for rotational roughness, corrosion, inadequate lubrication, physical damage, moisture or inadequate drainage due to build-up of zinc chromate paste in accordance with Step II, paragraph b of Schweizer Service Notice (SSN) No. N-59, dated October 9, 1968.

(1) If bearing rotational roughness, corrosion, inadequate lubrication, physical damage, moisture or inadequate drainage due to build-up of zinc chromate paste is found, replace the bearing with an airworthy bearing.

(2) If no bearing rotational roughness, corrosion, lack of lubrication, physical damage, moisture or inadequate drainage due to build-up of zinc chromate paste is found, thereafter, inspect the bearing in accordance with this paragraph upon attaining an additional 150 hours TIS.

(3) For replacement bearings, inspect in accordance with this paragraph upon attaining 150 hours TIS, unless the bearing reaches its 300 hour TIS retirement life limit prior to this inspection.

(c) For bearing, P/N 269A5050-73:

(1) Inspect the bearing for corrosion, rust, freedom of rotation, looseness, binding, nicks, burrs, cracks and lubrication. Thereafter, inspect the bearing at intervals not to exceed 600 hours TIS.

(2) As necessary, repack the bearing cavity in accordance with Schweizer Aircraft Corporation CKP-C-41 "Installation Instructions For 269 Series Helicopters, SA-269K-057-1 Main Rotor Thrust Bearing Kit," dated June 9, 1994.

(d) This AD establishes a retirement life of 300 hours TIS for bearings, P/Ns 269A5050-50 and -51 and a retirement life of 3,000 hours TIS for bearing, P/N 2695050-73. However, bearings, P/Ns 269A5050-50 and -51, with at least 275 hours TIS but less than 300 hours TIS, need not be retired until or before the accumulation of an additional 25 hours TIS.

(e) Inspect the thrust bearing nut (nut), P/N 269A1306-5, for corrosion and physical damage and determine whether the nut has been modified in accordance with Step III of SSN No. N-59, dated October 9, 1968.

(1) If corrosion or physical damage is found, replace the nut with an airworthy nut that has been modified in accordance with Step III of SSN No. N-59, dated October 9, 1968.

(2) If the nut has not been modified, modify the nut in accordance with Step III of SSN No. N-59, dated October 9, 1968.

(f) Inspect the interior of the main rotor mast (mast) for corrosion, physical damage, foreign materials, moisture or inadequate drainage due to a buildup of zinc chromate paste and determine whether the mast has been modified in accordance with Step II of SSN No. N-59, dated October 9, 1968 to install a drain hole.

(1) If corrosion or physical damage is found, replace the mast with an airworthy mast that has been modified in accordance with Step III of SSN No. N-59, dated October 9, 1968.

(2) If the interior of the mast has foreign materials, moisture or inadequate drainage due to a buildup of zinc chromate paste, clean the area with a suitable solvent in accordance with Step II of SSN No. N-59, dated October 9, 1968.

(3) If the mast has not been modified, modify the mast in accordance with Step III of SSN No. N-59, dated October 9, 1968.

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

(h) 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.

(i) The inspections, modifications, and replacements shall be done in accordance with Schweizer Service Notice No. N-59, dated October 9, 1968 and Schweizer Aircraft Corporation CKP- C-41 "Installation Instructions For 269 Series Helicopters, SA-269K-057-1 Main Rotor Thrust Bearing Kit," dated June 9, 1994. 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 Schweizer Aircraft Corporation, P.O. Box 147, Elmira, New York 14902. Copies may be inspected at the FAA, Office of the Assistant Chief Counsel, Room 663, 2601 Meacham Blvd., Fort Worth, Texas; or at the Office of the Federal Register, 800 North Capitol Street, NW., suite 700, Washington, DC.

(j) This amendment becomes effective on April 7, 1997.

A proposal to amend part 39 of the Federal Aviation Regulations (14 CFR part 39) by superseding AD 68-21-05, Amendment 39-672 (33 FR 15543, October 19, 1968), which is applicable to Model 269A helicopters, serial numbers (S/N) 0011 through 0979 (except Model TH-55A helicopters), Model 269A-1 helicopters, S/N 0001 through 0041, Model 269A- 2 helicopter, S/N 0001, and Model 269B, S/N 0001 through 0370, as revised by Amendment 39- 1055 (35 FR 12532, August 6, 1970), was published in the Federal Register on June 17, 1996 (61 FR 30548). That action proposed to require the same initial and repetitive inspections required by the existing AD (inspections of the main rotor thrust bearing (bearing) for bearing rotational roughness, corrosion, inadequate lubrication, physical damage, or excessive zinc chromate paste or moisture), but would extend the retirement life for certain bearings, and would remove the Model 269A-2 helicopter from, and add the Model TH-55Ahelicopters to the applicability of this AD.

Interested persons have been afforded an opportunity to participate in the making of this amendment. No comments were received on the proposal or the FAA's determination of the cost to the public. The FAA has determined that air safety and the public interest require the adoption of the rule as proposed, except for editorial changes and changes to paragraph (a) that more specifically state the actions that are required for those bearings having less than 300 hours time- in-service. The FAA has determined that these changes will neither increase the economic burden on any operator nor expand the scope of the AD.

The FAA estimates that 500 helicopters of U.S. registry will be affected by this AD, that it will take approximately 8 work hours per helicopter to accomplish the required actions, and that the average labor rate is $60 per work hour. Required parts will cost approximately $1,890 per helicopter. Based on these figures,the total cost impact of the AD on U.S. operators is estimated to be $1,185,000.

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. 106(g), 40113, and 44701.

39.13 - [Amended]
2. Section 39.13 is amended by removing Amendment 39-1055 (35 FR 12532, August 6, 1970), and Amendment 39-672 (33 FR 15543, October 19, 1968) and by adding a new airworthiness directive (AD), Amendment 39-9950, to read as follows: