AD 96-06-02

This amendment supersedes an existing airworthiness directive (AD), applicable to The Enstrom Helicopter Corporation Model (Enstrom) F-28A, F-28C, 280, and 280C helicopters, that currently requires an initial and repetitive visual inspections of the upper swashplate bearings for corrosion, and replacement of defective upper swashplate bearings with airworthy bearings. This amendment requires that the visual inspections apply to both the upper and lower swashplate bearings (bearings); expands the applicability to include the Model F-28C-2 helicopter; limits the applicability to those affected helicopters manufactured prior to January 1, 1981; establishes a retirement life of 1,200 hours time-in-service for certain bearings; and provides a corrected upper swashplate bearing part number. This amendment is prompted by the necessity to require visual inspections of the lower swashplate bearings; to expand the applicability to include the Model F-28C-2 helicopter; to establish a retirement life for certain bearings; and to correct the upper swashplate bearing part number from the existing AD. The actions specified by this AD are intended to prevent failure of the bearings and subsequent loss of control of the helicopter.

Final rule

96-06-02 THE ENSTROM HELICOPTER CORPORATION: Amendment 39-9539. Docket No. 93-SW-26-AD. Supersedes AD 76-06-11, Amendment 39-2560.

Applicability: Model F-28A, F-28C, F-28C-2, 280, and 280C helicopters, manufactured prior to January 1, 1981, 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 (e) 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 changedconfiguration 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 upper and lower swashplate bearings (bearings) and subsequent loss of control of the helicopter, accomplish the following:

(a) Within the next 10 hours time-in-service (TIS) after the effective date of this AD, and thereafter at intervals not to exceed 100 hours TIS since the last inspection, perform a visual inspection of the upper swashplate bearing, part number (P/N) Z993L13X3B, bearing number SKF 6013-RS, or ECD013-13, and lower swashplate bearing, P/N 5201SBKZZ-ABEC, or ECD009-11, for corrosion as follows:

(1) Lower the swashplate to lowest position with the collective control.

(2) Remove the plastic bearing seals from the upper and lower swashplate bearings using a blunt scribe.

(3) Using an inspection mirror, visually inspect the bearings for grease lubricant and any evidence of corrosion. Rotate the bearings and housing to reposition balls and race for complete inspection. For bearings found free of corrosion or defects, repack them with Exxon ANDOK-B grease or any MIL-G-18709A grease, and reinstall the bearing seals in accordance with the applicable maintenance manual.

(b) Replace any unairworthy bearing with an airworthy bearing in accordance with the applicable maintenance manual.

(c) Before further flight, after the effective date of this AD, remove all upper and lower swashplate bearings having 1,200 hours or more TIS, and replace them with airworthy bearings. For bearings with less than 1,200 hours TIS on the effective date of this AD, replace the bearings on or before attaining 1,200 hours TIS.

(d) Installation of revised upper swashplate bearing housing, P/N 28-16108-2, and lower swashplate bearing housing, P/N 28-16361-1, that are equipped with grease fittings and integral bearing shields as described in The Enstrom Helicopter Corporation Service Information Letter No. 0110, Revision B, dated March 18, 1993, constitutes terminating action for the requirements of this AD.

(e) An alternative method of compliance or adjustment of the compliance time that provides an acceptable level of safety may be used when approved by the Manager, Chicago 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, Chicago 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 Chicago Aircraft Certification Office.

(f) 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.

(g) The optional replacement permitted by paragraph (d) shall be done in accordance with The Enstrom Helicopter Corporation Service Information Letter No. 0110, Revision B, dated March 18, 1993. 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 The Enstrom Helicopter Corporation, Twin County Airport, P.O. Box 490, Menominee, Michigan 49858. 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.

(h) This amendment becomes effective on April 25, 1996.

A proposal to amend part 39 of the Federal Aviation Regulations (14 CFR part 39) by superseding AD 76-06-11, Amendment 39-2560, (41 FR 13906, April 1, 1976), which is applicable to Enstrom Model F-28A, F-28C, 280, and 280C helicopters manufactured prior to January 1, 1981, was published in the Federal Register on July 6, 1994 (59 FR 34584). That action proposed to require visual inspections of both the upper and lower swashplate bearings; to expand the applicability to include the Model F-28C-2 helicopter which was omitted in AD 76-06-11; to establish a retirement life of 1,200 hours time-in-service for certain upper and lower swashplate bearings; and to correct the upper swashplate bearing part number in the existing AD. That action also proposed an optional terminating action from the requirements of the AD and limited the applicability of the AD requirements to those affected model helicopters manufactured prior to January 1, 1981.

Interestedpersons 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 adding explanatory Note 1, relating to the scope of the applicability statement when modifications, alterations, or repairs have been made in the area subject to the requirements of the AD. Additionally, the FAA has revised the proposed estimated average labor rate from $55 per work hour to an estimated average labor rate of $60 per work hour in the preamble portion of this final rule. This revision will increase the estimated total cost impact of the AD from $1,105,500 to $1,122,000. 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 660 helicopters of U.S. registry will be affected by this AD, that it will take approximately 5 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 $1,400 per helicopter. Based on these figures, the total cost impact of the AD on U.S. operators is estimated to be $1,122,000.

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 USC 106(g), 40113, 44701.

39.13 - [Amended]
2. Section 39.13 is amended by removing Amendment 39-2560 (41 FR 13906, April 1, 1976), and by adding a new airworthiness directive (AD), Amendment 39-9539, to read as follows: