Electronic Engine Control Units

FAA Aviation Safety SPECIAL AIRWORTHINESS INFORMATION BULLETIN SUBJ: Electronic Engine Control Units SAIB: 2024-04 Date: 10/29/2024 This is information only. Recommendations aren’t mandatory.

Introduction

This Special Airworthiness Information Bulletin (SAIB) alerts owners, operators, and maintainers of Pratt & Whitney Canada Corp. (P&WC) PW305A engines equipped with Electronic Engine Control (EEC) units, part number (P/N) 31B4741 (vendor P/N 1240KDC) manufactured by Smiths (affected EEC units) of an increased rate of in-flight shutdown (IFSD) events due to failure of these units. PW305A engines installed on Learjet 60 aircraft serial numbers 001 through 128 are equipped with these affected EEC units; Learjet 60 aircraft starting with serial number 129 and higher are equipped with upgraded EEC units and are not subject to the airworthiness concern in this SAIB. This SAIB is also issued to inform owners, operators, and maintainers that repair and support of the affected EEC units is no longer available.

At this time, the airworthiness concern is not an unsafe condition that would warrant airworthiness directive (AD) action under Title 14 of the Code of Federal Regulations (14 CFR) part 39.

Background

A P&WC investigation determined that failures of affected EEC units, and the aging effect of their internal components, are attributed to a recent notable increase of IFSDs.

In addition to these failures and aging concerns, manufacturing of the affected EEC units ended in 1998 and several sub-components are no longer available. In 2020, P&WC issued Service Bulletin 24434, Revision 4, dated April 20, 2020 (P&WC SB 24434), which specifies replacing the EEC units and recommends accomplishing that replacement by September 30, 2021. P&WC then issued Service Information Letter No. PW300-201, dated January 25, 2021 (P&WC SIL PW300-201), to announce that support of affected EEC units would cease on September 30, 2021 and that the spares pool was depleted.

Recommendations

The FAA recommends that owners, operators, and maintainers of the affected PW305A engines: 1) At the earliest opportunity, replace the EEC in accordance with SB 24434 and 2) Review SIL PW300-201.

Note 1 - P&WC SB 24434 specifies other engine and airframe Service Bulletins be incorporated prior to, or in conjunction with, PW&C SB 24434. Note 2 - According to P&WC some costs may be covered under warranty or repair program plans, thereby reducing the cost impact on affected operators.

For Further Information Contact

Barbara Caufield, Aerospace Engineer, 1200 District Avenue, Burlington, MA 01803; phone: (781) 238-7146; email: [email protected].

For Related Service Information Contact

For further information regarding the P&WC service information, contact your local P&WC Field Service Manager; the P&WC Customer First (CFirst) Centre, phone: (800) 268-8000 or email: [email protected]; or Pratt & Whitney Canada Corp., 1000 Marie-Victorin, Longueuil, Quebec, Canada, J4G 1A1; phone: (800) 268-8000; website: www.pwc.ca.