80-10-04 R1 BELL: Amendment 39-3770 as amended by Amendment 39-4060. Applies to all Model 47 series helicopters and military Model H-13, OH-13, and TH13T series helicopters certificated in all categories that are equipped with tail rotor blades, P/N 47-642-102, except for those helicopters equipped with Franklin (or Aircooled Motors) engines. (Airworthiness Docket No. 67-SW-68.)
Compliance required as indicated.
To prevent possible failure of tail rotor blades, P/N 47-642-102, due to fatigue cracks, accomplish the following:
(a) Blades with 250 or more hours' time in service on the effective date of this AD must be removed from service within the next 50 hours' time in service and must be destroyed.
(b) Blades with less than 250 hours' time in service on the effective date of this AD must be removed from service prior to or on attaining 300 hours' time in service and must be destroyed on attaining 300 hours' total time in service.
(c) Prior to further flight after November 30, 1981, install improved tail rotor blades, P/N 47-642-117, unless already accomplished, in accordance with Bell Helicopter Textron Service Instruction No. 428 (47G-2A, G-2A-1, G-3, G-3B, G-3B-1, G-3B-2, G-4, G-4A, G-5, J-2, and J-2A) or No. 438 (47G and 47G-2), as appropriate, or data approved by the Chief, Engineering and Manufacturing Branch, FAA, Southwest Region.
(d) The helicopters may be flown in accordance with FAR 21.197 to a base where compliance with this AD can be performed.
(e) Equivalent means of compliance with paragraph (c) may be approved by the Chief, Engineering and Manufacturing Branch, FAA, Southwest Region.
(f) This AD applies to modified versions of the military H-13, OH-13, and TH-13T series helicopter models. Examples of such modified versions are the Continental Copters or Tomcat helicopters, OH-13H/Tomcat Mark 5 series and 6 series, or the Texas Helicopter OH-13/M74 series helicopters.
NOTE: The inspections and checks specified in AD 70-10-08, Amdt. 39-983, as amended by Amdt. 39-1063 and Amdt. 39-2642, have not been canceled or superseded by this AD and are still required.
(Bell Helicopter Textron OSN 47-79-2, Service Bulletin 47-76-2, Alert Service Bulletin Nos. 47-79-3 and 47-79-4 pertain to this subject.)
Amendment 39-3770 became effective June 9, 1980.
This amendment 39-4060 becomes effective February 28, 1981.