Airworthiness Directive · Amendment 39-11856 · Pratt & Whitney PW4164, PW4168, and PW4168A Series Turbofan Engines
Pratt & Whitney PW4164, PW4168, and PW4168A Series Turbofan Engines
Superseded. A later AD replaced this one: AD 2000-16-02 R1. Comply with the one in force.
Pratt & Whitney (PW) PW4164, PW4168, and PW4168A series turbofan engines, with front pylon mount bolts, part numbers (P/Ns) 54T670 or 51U615, installed. These engines are installed on but not limited to Airbus Industrie A330 series airplances.
Note 1: This airworthiness directive (AD) applies to each engine identified in the preceding applicability provision, regardless of whether it has been modified, altered, or repaired in the area subject to the requirements of this AD. For engines that have been modified, altered, or repaired so that the performance of the requirements of this AD is affected, the owner/operator must request approval for an alternative method of compliance in accordance with paragraph (e) of this AD. The request should include an assessment of the effect of the modification, alteration, or repair on the unsafe condition addressed by this AD; and, if the unsafe condition has not been eliminated, the request should include specific proposed actions to address it.
This amendment supersedes an existing airworthiness directive (AD), applicable to Pratt & Whitney PW4164, PW4168, and PW4168A series turbofan engines. The current AD requires initial and repetitive torque checks for loose or broken bolts used to secure the engine to the airplane made from INCO 718 material (front pylon mount bolts). The current AD also requires the replacement of the bolts, if necessary, with new bolts, and establishes a new cyclic life limit for the front pylon mount bolt. This amendment adds requirements for initial and repetitive torque checks of front pylon mount bolts made from a new material, MP159, and initial and repetitive visual inspections of the primary mount thrust load path. This amendment is prompted by the use of front pylon mount bolts made from MP159 material and fatigue testing that shows that the forward engine mount bearing housings have insufficient fatigue life expectancy. The actions specified by this AD are intended to prevent front pylon mount bolt and primary mount thrust load path failure, which could result in an engine separating from the airplane.
To prevent front pylon mount bolt and primary mount thrust load path failure, which could result in engine separation from the airplance, accomplish the following:
(a) Perform initial and repetitive torque checks of INCO 718 material front pylon mount bolts, P/N 54T670, and replace, if necessary, with new bolts, in accordance with the Accomplishment Instructions of Pratt & Whitney (PW) Alert Service Bulletin (ASB) No. 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-in-service-since-new (CSN) on the effective date of this AD, accomplish the following in accordance with Part (A) of the Accomplishment Instructions of the SB:
(i) Perform an initial torque check prior to accumulating 1,250 CSN or at the next engine removal for cause, whichever occurs first.
(ii) Thereafter, perform torque checks at intervals not fewer than 750 or greater than 1,250 cycles in service (CIS) since last torque check, not to exceed 11,000 CSN.
(2) For front pylon mount bolts, P/N 54T670, with 1,000 or more CSN but fewer than 5,750 CSN on the effective date of this AD, accomplish the following in accordance with Part (A) of the Accomplishment Instructions of the SB:
(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 first.
(ii) Thereafter, perform torque checks at intervals not fewer than 750 or greater than 1,250 CIS since last torque check, not to exceed 11,000 CSN.
(3) For front pylon mount bolts, P/N 54T670, with 5,750 or more CSN on the effective date of this AD, accomplish the following in accordance with Part (B) of the Accomplishment Instructions of the SB:
(i) Perform an initial torque check within 250 CIS after the effective date of this AD, or prior to the next engine removal for any cause, whichever occurs first.
(ii) Thereafter, perform torque checks at intervals not fewer than 750 or greater than 1,250 CIS since last torque check, not to exceed 11,000 CSN.
(4) Prior to further flight, replace all four bolts in accordance with Part (A), Paragraph 1(D) of the Accomplishment Instructions of the SB, if any of the bolts are loose or broken.
(b) This AD establishes a new life limit of 11,000 CSN for front pylon mount bolts, P/N 54T670. Except as provided in paragraph (e) of this AD, no front pylon mount bolts, P/N 54T670, may exceed this new life limit after the effective date of this AD.
(c) Perform initial and repetitive torque inspections of front pylon mount bolts, P/N 51U615, in accordance with the Accomplishment Instructions of PW ASB PW4G-100-A71-20, dated December 9, 1999, as follows:
(1) For front pylon mount bolts with fewer than 1,000 CSN on the effective date of this AD, perform the initial torque inspection at the earlier of the following:
(i) Before accumulating 1,250 CSN, or
(ii) The next engine removal for any cause.
(2) For front pylon mount bolts with 1,000 or more CSN on the effective date of this AD, perform the initial torque check at the earlier of the following:
(i) Within 250 CIS after the effective date of this AD, or
(ii) The next engine removal for any cause.
(3) Thereafter, perform torque inspections at intervals not fewer than 750 or greater than 1,250 CIS since last torque inspection.
(4) Prior to further flight, replace all four bolts, in accordance with Paragraph 1(D) of the Accomplishment Instructions of the ASB, if any are loose or broken.
(d) Perform initial and repetitive visual inspections of the primary mount thrust load path, in accordance with the Accomplishment Instructions of PW ASB PW4G-100-A71-18, Revision 1, dated December 9, 1999, 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 or more CSN on the effective date of this AD, perform the initial visual inspection at the earlier of the following:
(i) Within 250 CIS after the effective date of this AD, or
(ii) The next engine removal for any cause.
(3) Thereafter, perform visual inspections at intervals not fewer than 750 or greater than 1,250 CIS since last visual inspection.
(4) Prior to further flight, replace all cracked parts with serviceable parts and inspect the primary thrust load path components in accordance with Paragraph 4 of the accomplishment instructions of the SB.
The aircraft, engines and makers this AD names, by the model designations in its text. A model listed here may still be outside the AD's serial ranges.
