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.