FAA  Airworthiness Directive Review - Pratt & Whitney 4000 series engine In-flight Shut Down (IFSD) due to air/oil heat exchanger Corrosion owing to Long Groundings !

FAA  AD to address Corrosion issues of  Certain PW PW4000 series Engine air/oil heat exchanger  !

FAA issues  Airworthiness Directive : The FAA is adopting a new airworthiness directive (AD) 2022-07-13 for all Pratt & Whitney Division (PW) PW4074, PW4074D, PW4077, PW4077D, PW4084D, PW4090, and PW4090-3 model turbofan engines.

► Background of the AD :

An in-flight shutdown (IFSD) of an engine due to an air/oil heat exchanger leak caused by corrosion and subsequent investigation by the manufacturer that revealed additional air/oil heat exchanger leaks.

On November 9, 2021, a Boeing Model 777 airplane, powered by PW PW4077 engines, on a ferry flight from San Francisco, CA to Honolulu, HI, experienced an oil leak on the number 1 engine that resulted in an IFSD and air turnback to San Francisco , CA.

A post-flight inspection revealed that the oil leak was from the air/oil heat exchanger. After further investigation, the manufacturer determined that the air/oil heat exchanger leak was due to corrosion.

► Consequences:

This condition , if not addressed , could result in low oil pressure , failure of one or more engines , IFSD, loss of engine thrust control, reduced control of the airplane, and loss of the airplane.

► Required Actions by the AD :

► Within 30 days prior to the first flight after the effective date of this AD, perform an inspection for leaks of the air/oil heat exchanger in accordance with the Accomplishment Instructions, paragraph 3., of Pratt & Whitney Special Instruction No. 255F-21A , dated February 15, 2022.

► If any air/oil heat exchanger fails the inspection required by above paragraph, before further flight, remove the air/oil heat exchanger and replace with a part eligible for installation.

► Parts Eligibility : 

► A new air/oil heat exchanger with zero CSN , or

► An overhauled air/oil heat exchanger with zero cycles since last overhaul, or

► An air/oil heat exchanger that has passed the inspection required by the Actions segment of this AD.

► Pratt & Whitney (OEM) action : 

► According to the manufacturer, the lack of operation may have exacerbated corrosion on the air/oil heat exchanger. Pratt & Whitney Special Instruction No. 255F-21A, dated February 15, 2022.

► This special instruction specifies procedures for performing an inspection of the air/oil heat exchanger and, depending on the results of the inspection, replacement of the air/oil heat exchanger.

► This special instruction also specifies procedures for storing an air/oil heat exchanger after the inspection.

► Effective Date :

This airworthiness directive (AD) becomes effective on May 2, 2022. 

Source - FAA  / Picture for representation.