AD 2007-25-14 Airworthiness Directives; Agusta S.p.A. Model AB139 and AW139 Helicopters

Models named: AB139, AW139. Read the applicability below — it usually turns on serial or part numbers too.

This AD applies to Model AB139 and AW139 helicopters, all serial numbers, except 31002, 31003, 31004 and 31007, with tailpipe assemblies, part number (P/N) 3G7800L00131 (LH) or 3G7800L00231 (RH), certificated in any category. Reason (d) The mandatory continued airworthiness information (MCAI) states: Field reports have shown that the Agusta AB/AW139's Tailpipe Assembly is prone to cracks. To prevent any cracks from developing into failure of the exhaust tailpipe assembly * * * Actions and Compliance Continuing Requirements (e) Before further flight, and thereafter at intervals not to exceed 25 hours time-in-service (TIS), access the rear areas of each tailpipe assembly by removing the rear cowlings. (1) Visually inspect each tailpipe assembly inside the cowling for a crack. If you find a crack, before further flight, replace the cracked tailpipe assembly with an airworthy tailpipe assembly. (2) Visually inspect the structure surrounding each tailpipe assembly for overheating. If you find areas of overheating in the structure surrounding each tailpipe assembly, inspect for overheating in the underlying structure including on the upper deck thermal protection. Repair any damaged areas before further flight. (3) Visually inspect at the internal part of the tailpipe assembly exhaust outside the cowling as depicted by Area A, Figure 1, of Agusta Bollettino Tecnico No. 139-069, Revision A, dated November 8, 2006 (ABT). (i) Clean the end of each tailpipe assembly with a cloth. While applying slight pressure on it, inspect for a crack using a flashlight. (ii) Inspect each tailpipe assembly toward the centerline of the helicopter for a crack using a flashlight. (iii) Inspect each tailpipe assembly toward the outboard side of the helicopter for a crack using a mirror and a flashlight. New Requirements (f) If you find a crack in the exhaust area outside the cowling , do the following: (1) If any crack turns off abruptly (at an angle of greater than 45°) from the original direction, before further flight, replace that tailpipe assembly with an airworthy tailpipe assembly. (2) If you find only one crack in a tailpipe assembly and the crack does not make an abrupt turn and is 50mm or less in length— (i) Stop-drill the crack with a No. 30 drill bit, or (ii) Repair that tailpipe assembly in accordance with the Compliance Instructions, paragraph 7) d), of the ABT. (iii) If you choose to stop-drill the crack as indicated in paragraph (f)(2)(i) of this AD, thereafter, before the first flight of each day, inspect the stop-drill hole to determine whether another crack has started at the stop-drill hole. If you find during any inspection that another crack has started, before further flight, replace that tailpipe assembly with an airworthy tailpipe assembly. (3) If you find more than one crack and no crack makes an abrupt turn as stated in paragraph (f)(1) of this AD and the cracks are within the allowable limits stated in the Compliance Instructions, paragraph 7) d), of the ABT, repair the tailpipe assembly in accordance with the Compliance Instructions, paragraph 7) d) of the ABT. (g) Repairing or replacing the affected tailpipe assembly does not constitute terminating action for the repetitive inspection as required by paragraph (e) of this AD. Differences Between the FAA AD and the MCAI (h) None.