Flight Management Computing Software System

1 FAA Aviation Safety SPECIAL AIRWORTHINESS INFORMATION BULLETIN SUBJ: Flight Management Computing Software System SAIB: AIR-20-19 Date: November 16, 2020 This is information only. Recommendations aren’t mandatory.

Introduction

This Special Airworthiness Information Bulletin (SAIB) advises owners and operators of The Boeing Company Model 777 airplanes, and Model 787-8, -9, and -10 airplanes of failure of the auto-throttle to disconnect during a balked landing.

Background Several in-service reports have been received from operators that the auto-throttle remained engaged in the IDLE mode when the flight crew advanced the thrust levers to conduct a balked landing (a go- around initiated after touchdown, but before the thrust lever selection). Once airborne, the thrust levers moved back to idle. This caused a reduction in airspeed and eventual stick shaker activation. The 787 Flight Management Block Point 4 (FMF BP4) software currently installed introduced an auto-throttle software anomaly, which disables one element of the automatic throttle disconnect logic.

The 777 Airplane Information Management System (AIMS) V17B software introduced a similar auto-throttle anomaly that kept the auto-throttle connected in IDLE mode when the flight crew advanced the thrust levers forward to conduct a go-around after the airplane touched the ground. Once airborne, the auto-throttle remains in IDLE and moves the thrust levers to idle. This causes a reduction in airspeed and possible stick shaker activation.

The Boeing Company issued Boeing Flight Crew Operations Manual Bulletins TBC-108, dated March 25, 2020, and TBC-158, dated March 24, 2020, for Model 787 and Model 777 airplanes, respectively. These operations manuals include more detailed information regarding this anomaly and provide operating instructions to the flight crew for conducting a balk landing and a go-around.

Boeing and its supplier are currently working on developing operational program software to correct this auto-throttle software anomaly issue. The FAA is considering issuing rulemaking to mandate installation of this software update when developed, approved, and available.

Recommendations

The FAA recommends that all owners and operators of the affected airplanes incorporate the actions outlined in the referenced operations manuals at the earliest opportunity.

For Further Information Contact

Hassan Ibrahim, Aerospace Engineer, Systems and Equipment Section, FAA, Seattle ACO Branch, 2200 South 216th St., Des Moines, WA 98198, at phone and fax: (206) 231-3653; email: [email protected].

2 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; https://www.myboeingfleet.com; or www.myboeingfleet.com/ReverseProxy/Authentication.html.