AD 87-10-11

87-10-11 BELL HELICOPTER TEXTRON, INC. (BHTI): Amendment 39-5976. Final copy of Telegraphic AD. Applies to the following helicopters certificated in any category (Airworthiness Docket No. 87-ASW-22).

(a) Model 206A and 206B helicopters equipped with the following mast assemblies, P/N 206-010-332-121: Serial Numbers FAJF-58340 thru 58353, 58395 thru 58398, 58400, 58402 thru 58408, 58421 and 58423 thru 58434.

NOTE: The following model 206B serial numbered helicopters were delivered with the affected masts: 3933, 3934, 3937 thru 3940, 3942, 3944 thru 3946, 3953 thru 3955, and 3958.

(b) Model 206L, 206L-1, and 206L-3 helicopters equipped with the following mast assemblies, P/N 206-040-535-105: Serial Numbers NJF-935 thru 973, 1000, 1003, 1004, 1006 thru 1012, 1014 thru 1019, 1022 thru 1024, 1026, 1040 thru 1042, 1046, 1050 thru 1057, 1059, 1066, 1068, 1073, 1079, 1086, 1087, 1089 thru 1097, 1099, 1101, 1102, 1123, 1124, 1129, 1135, 1141, 1143, 1145, 1146, 1149, 1151, 1153, 1156, 1157, 1161, 1162, 1165, 1167, and 1169 thru 1172.

NOTE: The following Model 206L-3 serial numbered helicopters were delivered with the affected masts: 51173 thru 51175, 51178, 51179, 51181, 51183 thru 51185, 51187 thru 51191, 51194 thru 51205, and 51208 thru 51211.

Compliance is required as indicated, unless already accomplished.

To prevent failure of the main rotor mast, accomplish the following:

(a) Before further flight, determine if an affected serial number main rotor mast is installed on the helicopter.

(b) Within the next 25 hours' time in service after receipt of this AD but no later than May 31, 1987, remove the affected serial number main rotor mast from service and replace it with an airworthy part.

(c) An alternate method of compliance or adjustment of the compliance time, which provides an equivalent level of safety, may be used when approved by the Manager, Helicopter Certification Branch, Aircraft Certification Division, FAA, Southwest Region, Fort Worth, Texas 76193-0170.

NOTE: Bell Helicopter Alert Service Bulletin Nos. 206-87-37, dated 4/23/87 and 206-87-44, dated 4/23/87 pertain to this AD.

This amendment becomes effective August 8, 1988, as to all persons except those persons to whom it was made immediately effective by Priority Letter AD No. 87-10-11 issued May 19, 1987, which contained this amendment.