AD 81-12-05 ACTIVE

81-12-05 HAMILTON STANDARD: Amendment 39-4131. Applies to all Hamilton Standard 24PF propellers with air-melt barrels, Part Number 772531-1, installed on DeHavilland DHC-7 aircraft. (Note: This AD does not apply to propellers with vacuum-melt barrels, Part Number 772531-2.)

Compliance is required as indicated. To determine the presence of spalling in the bearing raceway surfaces of the barrel and blade split races, visually inspect in accordance with the procedure contained in the accomplishment instruction section of Hamilton Standard Service Bulletin HS Code 24PF No. 17, Revision 2 dated April 10, 1981, or later FAA approved revision, or equivalent means approved by the Chief, Engineering and Manufacturing Branch, Great Lakes Region.

Inspect in accordance with the following schedule:

a. For propellers with 2,900 hours or more time in service since new, compliance is required within the next 100 hours time in service after the effective date of this AD, unless already accomplished within the last 1,400 hours time in service, and thereafter at intervals not to exceed 1,500 hours time in service from the last inspection required by this AD.

b. For propellers with less than 2,900 hours time in service since new, compliance is required prior to the accumulation of 3,000 hours time in service, unless already accomplished within the last 1,400 hours time in service, and thereafter at intervals not to exceed 1,500 hours time in service from the last inspection required by this AD.

c. Propellers with spalled barrels must be removed from service prior to further flight and replaced with airworthy propellers. Propellers with spalled split race(s) must have the race(s) replaced prior to further flight in accordance with Service Bulletin 24PF-17, Revision 2 dated April 10, 1981, or later FAA approved revision.

d. Results of all propeller inspections required by this AD, including serial numbers and times in service, are to be forwarded toFederal Aviation Administration, Engineering and Manufacturing Branch, AGL-210, 2300 East Devon Avenue, Des Plaines, Illinois 60018. (Reporting approved by the Office of Management and Budget under OMB Number 04-R0174.)

e. After successfully completing two consecutive 1500 hour inspections without seeing any evidence of barrel or bearing race spalling, the repetitive 1500 hour inspections required by this AD may be discontinued.

f. Upon request of an operator, the Chief, Engineering and Manufacturing Branch, AGL-210, Federal Aviation Administration, Great Lakes Region, may adjust the compliance time specified in this AD provided such requests are made through an FAA Maintenance Inspector, and the request contains substantiating data to justify the request for that operator.

g. For purpose of this AD, an FAA-approved equivalent must be approved by the Chief, Engineering and Manufacturing Branch, AGL-210, Federal Aviation Administration, Great Lakes Region.

The manufacturer's specifications and procedures identified in this directive are incorporated herein and made part hereof pursuant to 5 U.S.C. 552(a)(1). All persons affected by the directive who have not already received these documents from the manufacturer may obtain copies upon request to Hamilton Standard, Division of United Technologies Corporation, Windsor Locks, Connecticut 06096. These documents may also be examined at the Great Lakes Regional Office, FAA, 2300 East Devon Avenue, Des Plaines, Illinois 60018.

This amendment becomes effective June 15, 1981.