AD 92-13-10

92-13-10 BELL HELICOPTER TEXTRON, INC. (BHTI): Amendment 39-8280. Docket No. 92-ASW-17. Supersedes Priority Letter AD 91-24-16, issued November 18, 1991, Docket No. 91-ASW-30.

Applicability: All BHTI Model 204B, 205A, 205A-1, 205B, 212, and 412 helicopters, certificated in any category.

Compliance: Required as indicated, unless already accomplished.

To prevent possible failure of a tail rotor driveshaft hanger bearing that could result in failure of the tail rotor driveshaft and subsequent loss of tail rotor control, accomplish the following:

(a) Before further flight, after the effective date of this AD, determine the serial number (S/N) etched on the seal area of the tail rotor driveshaft hanger bearings, part number (P/N) 204-040-623-003 or 005. If the bearing has no permanently marked S/N, has a P/N 204- 040-623-003 with S/N T0001 through T1743 or N4000 and subsequent, or has a P/N 204-040- 623-005 with S/N NC3000 and subsequent; no further action is required by this AD.

(b) Within the next 100 hours' time in service after the effective date of this AD, replace the tail rotor driveshaft hanger bearings and bearing assemblies as follows in accordance with the applicable BHTI maintenance, repair, and overhaul manuals:

(1) For the Model 204B helicopters, remove each P/N 204-040-623-005 bearing that has a S/N with a prefix of T or N; replace with a P/N 204-040-623-005 bearing that has no S/N or a S/N of NC3000 and subsequent. This paragraph applies to parts with a prefix of N, but not with a prefix of NC.

(2) For the Model 205A, 205A-1 and 212 helicopters, accomplish the following:

(i) Remove each P/N 204-040-623-003 bearing that has a S/N T1744 and subsequent or N0001 through N3999; replace with a P/N 204-040-623-003 bearing that has no S/N, a S/N from T0001 through T1743 or a S/N of N4000 and subsequent.

(ii) Remove each bearing with P/N 204-040-623-005 that has a S/N prefix of T or N; replace with a P/N204-040-623-005 bearing that has no S/N or a S/N of NC3000 and subsequent.

(3) For the Model 205B and 412 helicopters, remove each P/N 204-040-623- 003 bearing that has a S/N T1744 and subsequent or N0001 through N3999; replace with a P/N 204-040-623-003 bearing that has no S/N, a S/N T0001 through T1743, or S/N of N4000 and subsequent.

(c) Before the first flight of each day, until the driveshaft hanger bearing is replaced in accordance with paragraph (b), accomplish the following inspection of the tail rotor driveshaft and tail rotor driveshaft hanger assemblies:

(1) Visually inspect the tail rotor driveshaft hanger bearings for grease leakage that continues for more than 10 hours' time in service after installation of a new bearing.

(2) Visually inspect the tail rotor driveshafts and driveshaft hanger assemblies for security and damage.

(3) Visually inspect the tail rotor driveshaft hanger assembly for an overheat condition and overheat indicator stripes for discoloration.

(4) Rotate the tail rotor driveshaft by hand while feeling the tail rotor driveshaft bearing housing for bearing binding or roughness.

(d) Before further flight, replace the tail rotor driveshaft hanger bearings with an airworthy part in accordance with the applicable BHTI maintenance, repair and overhaul manuals if the bearing assemblies exhibit signs of overheating, roughness or continued grease leakage.

(e) This AD supersedes Priority Letter AD 91-24-16, issued November 18, 1991, Docket No. 91-ASW-30.

(f) An alternative method of compliance or adjustment of the compliance time, which provides an acceptable level of safety, may be used when approved by the Manager, Rotorcraft Certification Office, ASW-170, FAA, 4400 Blue Mound Road, Fort Worth, Texas. The request shall be forwarded through an FAA Principal Maintenance Inspector, who may concur or comment and then send it to the Manager, Rotorcraft Certification Office.

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

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

(h) This amendment becomes effective February 23, 1993.