AD 2006-16-05 Airworthiness Directives; Pratt & Whitney PW4164, PW4168, and PW4168A Series Turbofan Engines

This AD applies to Pratt & Whitney (PW) PW4164, PW4168, and PW4168A series turbofan engines, with front pylon mount bolts, part number (P/N) 54T670 or 51U615, installed. These engines are installed on, but not limited to, Airbus A330 series airplanes.

You are responsible for having the actions required by this AD performed within the compliance times specified unless the actions have already been done. INCO 718 Material Bolts Torque Checks (f) Perform initial and repetitive torque checks of INCO 718 material front pylon mount bolts, P/N 54T670, and replace, if necessary, with new bolts, using the Accomplishment Instructions of PW Alert Service Bulletin (ASB) PW4G-100-A71-9, Revision 1, dated November 24, 1997, as follows: (1) For front pylon mount bolts, P/N 54T670, with fewer than 1,000 cycles-since-new (CSN) on the effective date of this AD, do the following using Part (A) of the Accomplishment Instructions of the ASB: (i) Perform an initial torque check before accumulating 1,250 CSN or at the next engine removal for cause, whichever occurs sooner. (ii) Thereafter, perform torque checks at intervals of no fewer than 750 or no more than 1,250 cycles-in-service (CIS) since last torque check. (2) For front pylon mount bolts, P/N 54T670, with 1,000 CSN or more but fewer than 5,750 CSN on the effective date of this AD, do the following using Part (A) of the Accomplishment Instructions of the ASB: (i) Perform an initial torque check within 250 CIS after the effective date of this AD, or at the next engine removal for any cause, whichever occurs sooner. (ii) Thereafter, perform torque checks at intervals of no fewer than 750 or no more than 1,250 CIS since last torque check. (3) For front pylon mount bolts, P/N 54T670, with 5,750 CSN or more on the effective date of this AD, do the following using Part (B) of the Accomplishment Instructions of the ASB: (i) Perform an initial torque check within 250 CIS after the effective date of this AD, or before the next engine removal for any cause, whichever occurs sooner. (ii) Thereafter, perform torque checks at intervals of no fewer than 750 or no more than 1,250 CIS since last torque check. (4) Remove from service front pylon mount bolts P/N 54T670, at or before reaching the life limit of 11,000 CSN. (5) Before further flight, replace all four bolts using Part (A), Paragraph 1(D) of the Accomplishment Instructions of the ASB, if any of the bolts are loose or broken. MP159 Material Bolts Inspections (g) Perform initial and repetitive torque checks of front pylon mount bolts, P/N 51U615, using the Accomplishment Instructions of PW ASB PW4G-100-A71-32, dated April 15, 2005, as follows: (1) For front pylon mount bolts with fewer than 2,200 CSN on the effective date of this AD, perform the initial torque inspection before accumulating 2,700 CSN, or at the next engine removal for any cause, whichever occurs sooner. (2) For front pylon mount bolts with 2,200 CSN or more on the effective date of this AD, perform the initial torque check within the next 500 CIS, or at the next engine removal for any cause, whichever occurs sooner. (3) Thereafter, perform torque inspections at intervals not to exceed 2,700 CIS since last torque inspection. (4) Before further flight, replace all four bolts using Paragraph 1.E. of the Accomplishment Instructions of the ASB, if any are loose or broken. Primary Mount Thrust Load Path Inspections (h) Perform initial and repetitive visual inspections of the primary mount thrust load path using the Accomplishment Instructions of PW ASB PW4G-100-A71-18, Revision 2, dated January 15, 2002, as follows: (1) For forward engine mount assemblies with fewer than 1,000 CSN on the effective date of this AD, perform the initial visual inspection at the earlier of the following: (i) Before accumulating 1,250 CSN; or (ii) The next engine removal for any cause. (2) For forward engine mount assemblies with 1,000 CSN or more on the effective date of this AD, perform the initial visual inspection within 250 CIS after the effective date of this AD, or the next engine removal for any cause, whichever occurs sooner. (3) Thereafter, perform visual inspections at intervals of no fewer than 750 or no more than 1,250 CIS since-last-visual-inspection. (4) Before further flight, replace all cracked parts with serviceable parts and inspect the primary thrust load path components using Paragraph 4 of the Accomplishment Instructions of the ASB. Terminating Action (i) Replacement of the forward engine mount bearing housing, P/N 59T794 or P/N 54T659 with P/N 52U420, using SB PW4G-100-71-22, dated January 15, 2002, constitutes terminating action to the inspection requirements of paragraph (h) of this AD. Alternative Methods of

This AD results from analysis by the manufacturer that MP159 material pylon bolts do not meet the full life cycle torque check interval requirement, in a bolt-out condition. We are issuing this AD to prevent front pylon mount bolt and primary mount thrust load path failure, which could result in an engine separating from the airplane.