AD 72-08-04

72-08-04 HARTZELL: Amdt. 39-1427. Applies to all models of Hartzell T10173( ) and T10176( ) type blades including serial numbers listed below installed on Hartzell HC-B3TN-2, HC-B3TN-3, HC-B3TN-5, HC-B3TF-7, and HC-B4TN-3 series propellers used on United Aircraft of Canada PT6A-, AiResearch TPE331- and Allison 250-B type engines.

Blade Serial Numbers

All serial numbers without prefix letters, all serial numbers prefixed with letter "A" and all serial numbers with prefix letter "B" up to serial No. B85887, except for the following serial numbers:

A97324 B63327 B80895 B82883 A97352 B63354 B80908 B82891 A98330 B63431 B80911 B82894 B38602 B63441 B80988 B82895 B39183 B69570 B82181 B82898 B39356 B71482 B82182 B82900 B40809 B71483 B82215 B82902 B40828 B75009 B82565 B82905 B41002 B75037 B82566 B82908 B41387 B75322 B82577 B84129 B41886 B76844 B82579 B84168 B41893 B76847 B82586 B84169 B44241 B76865 B82595 B84187B44343 B78383 B82598 B84192 B49153 B78386 B82599 B84193 B53160 B78428 B82603 B84222 B53246 B79430 B82607 B84227 B53249 B79435 B82685 B84230 B53264 B79454 B82694 B84243 B63036 B80547 B82699 B84245 B63039 B80548 B82706 B84254 B63122 B80553 B82710 B84294 B63127 B80698 B82711

B63131 B80715 B82876

B63294 B80717 B82878

Compliance required as indicated, unless already accomplished.

A. To prevent propeller blade failures, accomplish the following:

1. Propellers with a total of 1400 or more hours in service, inspect in accordance with paragraph (A)(5) within the next 100 hours in service after the effective date of this directive. If no cracks are found, shot peen propeller blade balance hole and service in accordance with Hartzell Bulletin No. 97, dated 1 December 1971, or equivalent procedure approved by the Chief, Engineering and Manufacturing Branch, Eastern Region.

2. Propellers with less than 1400 total hours in service, inspect in accordance with paragraph (A)(5) prior to the accumulation of 1500 total hours in service. If no cracks are found, shot peen propeller blade balance hole and service in accordance with Hartzell Bulletin No. 97, dated 1 December 1971, or equivalent procedure approved by the Chief, Engineering and Manufacturing Branch, Eastern Region.

3. Propellers whose total hours in service are unknown will be assumed to have a total of 1400 hours minimum and thus fall within the requirements for inspection and shot peening in accordance with paragraph (A)(1).

4. Propellers whose total time in service is unknown, inspect each blade for cracks by dye penetrant method or an equivalent method approved by the Chief, Engineering and Manufacturing Branch, Eastern Region, in the area of 2 to 6 inches outboard of the blade clamp (excluding the de-icers), within the next 15 hours' time in service after the effective date of this directive. Reinspect every 15 hours' time in service from last inspection until the inspection and shot peening requirements in accordance with paragraph (A)(1) are accomplished. If a cracked blade is found, remove and replace propeller before further flight with a propeller having blades to which this AD does not apply or have been inspected and altered in accordance with this directive.

5. Remove propeller from the aircraft and remove blades from hub. If lead wool is installed in balance hole, remove in accordance with Hartzell Bulletin No. 97 dated 1 December 1971, or equivalent procedure approved by the Chief, Engineering and Manufacturing Branch, Eastern Region. Inspect interior surfaces of balance hole for cracks in accordance with Hartzell Bulletin No. 97, Appendix "B", dated 1 December 1971, or equivalent procedure approved by the Chief, Engineering and Manufacturing Branch, Eastern Region. Replace any cracked blades before flight with blades to which this AD does not apply or which have been inspected and altered in accordance with this directive.

B. Propeller blade retirement for Beech 99 and A99 type aircraft. This applies only to blades affected by this directive.

1. Within 1500 hours' time in service after accomplishment of the inspection and shot peening requirements in accordance with paragraph (A)(1), remove the propeller(s) from the aircraft. Remove the blades from the hub, and replace with T10173- Category II type blades in accordance with instructions in Hartzell Overhaul Manual 118. Replaced blades must be retired from any further service in aircraft.

2. Propellers which have not been inspected and shot peened in accordance with paragraph (A)(2) as of the effective date of this directive may comply with the blade replacement requirements of paragraph (B)(1), in lieu of compliance with the requirements in paragraph (A)(2).

(Hartzell Letter to Propeller Repair Stations dated 21 January 1972 pertains to this subject.)

This AD supersedes AD 71-26-04.This amendment is effective April 11, 1972.