AD 71-07-01

71-07-01 PRATT & WHITNEY: Amdt. 39-1179 as amended by Amendment 39-1279. Applies to Pratt & Whitney Aircraft JT8D-1, -1A, -7, and -7A turbofan engines using Front Compressor Front Hub Part Nos. 504101 and 515201. Pratt & Whitney Aircraft Alert Service Bulletin No. 2944, Revision No. 5, lists the engine and hub serial numbers affected by this airworthiness directive. The manufacturer's serial numbers described in the applicability statement are incorporated herein and made a part hereof pursuant to 5 U.S.C. 552(a)(1). All persons affected by this directive who have not already received the referenced Alert Service Bulletin from the manufacturer may obtain copies upon request to Pratt & Whitney, Main Street, East Hartford, Conn. These documents may also be examined at Eastern Region headquarters, JFK International Airport, Jamaica, New York. A historical file on this A.D. which includes the incorporated material in full, is maintained by the FAA at its headquarters in Washington, D.C.and at the Eastern Region headquarters, Jamaica, New York.

Compliance required as indicated on all front compressor front hubs that have accumulated 6000 cycles or more in service.

1. To preclude failure of the front compressor front hub as a result of (a) possible surface defects in the blade slots or (b) possible loss of effectiveness of shotpeening in the blade slots accomplish the following on hubs listed in tables I and II of the above service bulletin.

a. Visually inspect, within the next 150 cycles in service and every 150 cycles in service thereafter until the hub is removed, the rear face and overhung shelf of the hub rim for cracks emanating out of the base of the acute corner of the dovetail slots, or

b. Inspect with an eddy current probe, within the next 150 cycles in service, unless already accomplished and every 400 cycles in service thereafter until the hub is removed, the rear overhung shelf of the hub rim for cracks emanating out of the base of the acute corner of the dovetail slots, or

c. Within the next 150 cycles in service, unless already accomplished and every 1500 cycles in service thereafter, remove all first stage compressor blades and inspect the blade slots of the hub with an eddy current probe for cracks emanating out of the base of the acute corner of the dovetail slots.

d. If any crack is found during any of the foregoing inspections replace hub before further flight.

e. It is permissible to use any of the three inspection procedures at the end of the preceding inspection period.

2. To preclude failure of the front compressor front hub from lack of shotpeening accomplish the following on hubs listed in table III of the above service bulletin.

a. Visually inspect, within the next 150 cycles in service, to determine whether the rim area of the hub has been shotpeened.

b. If the inspection confirms that the hub has not been shotpeened then the hub is to be inspected in accordance with paragraphs 1 (a) through (e) of this AD.

Upon submission of substantiating data through an FAA Maintenance Inspector by an owner or operator, the Chief, Engineering and Manufacturing Branch, Federal Aviation Administration, Eastern Region, may adjust the compliance time.

(Pratt & Whitney Aircraft Alert Service Bulletin No. 2944 Rev. 5 dated 12 August 1971 pertains to this subject.) Amendment 39-1179 was effective March 30, 1971 and was effective upon all recipients of the telegram dated October 16, 1970 which contained this Airworthiness Directive.

This amendment 39-1279 is effective September 7, 1971.