AD 86-03-03

86-03-03 PRATT & WHITNEY: Amendment 39-5219. Applies to Pratt & Whitney model JT9D-7R4D, 7R4E, and -7R4E4 turbofan engines.

Compliance is required as indicated unless already accomplished.

To prevent deterioration of fuel nozzle flow and spray cone angle characteristics which could lead to engine surge, overtemperature, or the inability to restart inflight, accomplish the following:

(a) Conduct a flow check on JT9D-7R4 series engine incorporating PW P/N 792842 and/or 794731 fuel nozzles following any on-wing cleaning procedure prior to returning the aircraft to service in accordance with PW Maintenance Manual P/N 785050, Chapter 73-13-07, Cleaning/Painting Section as revised by Temporary Revision 73-3, or FAA approved equivalent.

(1) A flow reduction of 10 percent or less is acceptable.

(2) A flow reduction greater than 10 percent but less than 20 percent requires selected fuel nozzles to be replaced with new or ultrasonically cleaned nozzles within 300flight cycles. The fuel nozzles may be replaced in quantities and locations as needed to restore the flow to 10 percent flow reduction or less.

(3) A flow reduction of 20 percent or greater requires selected fuel nozzles to be replaced with new or ultrasonically cleaned nozzles within 25 flight cycles. If there have been any unresolved aborted ground starts (since the last cleaning and flow check) that are not attributed to an ignition system fault or a mechanical problem which is unrelated to the fuel nozzles, fuel nozzles must be selectively replaced within 5 cycles. The fuel nozzles may be replaced in quantities and locations as needed to restore the flow to 10 percent flow reduction or less.

(b) Ground starts must be initiated using single ignition, either ignition selector position 1 or 2. If an aborted start is experienced using single ignition that is related to a fuel nozzle problem, the engine may be started on the opposite ignition system or dual ignition and the fuel nozzles must be cleaned and flow checked within 25 flight cycles in accordance with PW Maintenance Manual P/N 785050, Chapter 73-13-07, Cleaning/Painting Section as revised by Temporary Revision 73-3, or FAA approved equivalent.

The flow check limits in Paragraph (a) are applicable to Paragraph (b).

Aircraft may be ferried in accordance with the provisions of FAR 21.197 and 21.199 to a base where the AD can be accomplished.

Upon request, an equivalent means of compliance with the requirements of this AD may be approved by the Manager, Engine Certification Office, Aircraft Certification Division, New England Region, Federal Aviation Administration, 12 New England Executive Park, Burlington, Massachusetts 01803.

Upon submission of substantiating data by an owner or operator through an FAA maintenance inspector, the Manager, Engine Certification Office, Aircraft Certification Division, New England Region, Federal Aviation Administration, 12 New England Executive Park, Burlington, Massachusetts 01803, may adjust the compliance time specified in this AD.

PW Maintenance Manual P/N 785050, Chapter 73-13-07, Cleaning/Painting Section as revised by Temporary Revision 73-3 is incorporated herein and made a part hereof pursuant to 5 U.S.C. 552 (a)(1). (Boeing Maintenance Manual, Chapter 73-11-05, Cleaning/Painting Section is an equivalent means of compliance.) All persons affected by this directive who have not already received this document from the manufacturer may obtain copies upon request to Pratt & Whitney, Commercial Products Division, 400 Main Street, East Hartford, Connecticut 06108. This document also may be examined at the Office of the Regional Counsel, Rules Docket 85-ANE-8, Federal Aviation Administration, 12 New England Executive Park, Burlington, Massachusetts 01803.

This amendment becomes effective on March 14, 1986.