Engine Fuel and Control

1 FAA Aviation Safety SPECIAL AIRWORTHINESS INFORMATION BULLETIN SUBJ: Engine Fuel and Control SAIB: NM-18-33 Date: December 17, 2018 This is information only. Recommendations aren’t mandatory.

Introduction

This Special Airworthiness Information Bulletin (SAIB) is to advise registered owners and operators of The Boeing Company Model 717-200 airplanes; Model 737-700, -700C, -800, and -900ER series airplanes; Model 737-8 and -9 airplanes; Model 747-400, -400D, -400F, -8, and -8F series airplanes; Model 757-200, -200CB, -200PF, and -300 series airplanes; Model 767-200, -300, - 300F, -400ER, and -2C series airplanes; Model 787-8, -9, and -10 airplanes; Model MD-11 and MD-11F airplanes; and Model MD-90-30 airplanes of the potential for disengagement of the fuel control switch locking feature.

Based on an assessment utilizing the limited data currently 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. The FAA will continue to monitor this issue.

Background

The Boeing Company (Boeing) received reports from operators of Model 737 airplanes that the fuel control switches were installed with the locking feature disengaged. The fuel control switches (or engine start switches) are installed on the control stand in the flight deck and used by the pilot to supply or cutoff fuel to the engines. The fuel control switch has a locking feature to prevent inadvertent operation that could result in unintended switch movement between the fuel supply and fuel cutoff positions. In order to move the switch from one position to the other under the condition where the locking feature is engaged, it is necessary for the pilot to lift the switch up while transitioning the switch position. If the locking feature is disengaged, the switch can be moved between the two positions without lifting the switch during transition, and the switch would be exposed to the potential of inadvertent operation. Inadvertent operation of the switch could result in an unintended consequence, such as an in-flight engine shutdown.

Boeing informed the FAA that the fuel control switch design, including the locking feature, is similar on various Boeing airplane models. The table below identifies the affected airplane models and related part numbers (P/Ns) of the fuel control switch, which is manufactured by Honeywell.

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Airplane Model Honeywell P/N 717-200 3TL32-2-3D 737-700, -700C, -800, and -900ER 766AT613-3D 737-8 and -9 766AT613-3D 747-400, -400D, and -400F 3TL32-3D 747-400, -400D, -400F, -8, and -8F 4TL32-3D 757-200, -200CB, -200PF, and -300 3TL32-12A 767-200, -300, -300F, and -400ER 3TL32-3D 767-2C 50075622-001 787-8, -9, and -10 4TL837-3D MD-11 and MD-11F 3TL32-1-3D MD-90-30 3TL32-2-3D

Recommendations

The FAA recommends that all owners and operators of the affected airplanes incorporate the following actions at the earliest opportunity:

1) Inspect the locking feature of the fuel control switch to ensure its engagement. While the airplane is on the ground, check whether the fuel control switch can be moved between the two positions without lifting up the switch. If the switch can be moved without lifting it up, the locking feature has been disengaged and the switch should be replaced at the earliest opportunity.

2) For Boeing Model 737-700, -700C, -800, and -900ER series airplanes and Boeing Model 737- 8 and -9 airplanes delivered with a fuel control switch having P/N 766AT613-3D: Replace the fuel control switch with a switch having P/N 766AT614-3D, which includes an improved locking feature.

We request that owners and operators report any failure of the locking feature of the fuel control switch to Boeing (see contact information provided below). The report should include the date the failure occurred, the fuel control switch P/N, airplane model, airplane serial number, and airplane registration number. Under the provisions of the Paperwork Reduction Act (44 U.S.C. 3501 et seq.), the Office of Management and Budget (OMB) has approved the information collection contained in this SAIB, and assigned OMB Control Number 2120-0731.

For Further Information Contact

Tak Kobayashi, Aerospace Engineer, Propulsion Section, FAA, Seattle ACO Branch, AIR-784, FAA, Seattle ACO Branch, 2200 South 216th Street, Des Moines, WA 98198; phone and fax: 206-231- 3553; email: [email protected].

For Related Service Information Contact

Boeing Commercial Airplanes, Attention: Contractual & Data Services (C&DS), 2600 Westminster Blvd., MC 110-SK57, Seal Beach, CA 90740-5600; telephone 562-797-1717.