The Federal Aviation Administration (FAA) has issued a new Airworthiness Directive (AD) for Boeing 787-8, 787-9, and 787-10 airplanes, effective October 23, 2024. This directive addresses safety concerns related to erroneous autothrottle (A/T) behavior during balked landings and potential inaccuracies from the low range radio altimeter (LRRA), as well as possible deficiencies in low airspeed protections and crew alerting systems.
The directive was prompted by incidents where the autothrottle system exhibited erroneous behavior during critical flight phases such as balked landings, with the system failing to properly adjust thrust levels. Additionally, the low range radio altimeter (LRRA) has shown potential for erroneous readings, which can lead to inadequate airspeed protections. These issues could result in unsafe conditions, including runway overruns or controlled flight into terrain.
Required Actions
The AD mandates updating the Thrust Management (TM) and Displays and Crew Alerting (DCA) Operational Program Software (OPS) on the affected Boeing 787 models. The software update corrects potential errors in the A/T system and LRRA to ensure accurate performance and enhance overall flight safety.
Operators must comply with the AD within six months of its effective date. The directive allows for compliance using either the latest or previous versions of the Boeing Alert Requirements Bulletins, provided the necessary software updates have been applied.
Several airlines, including Air Canada and Qatar Airways, requested modifications to the AD to permit compliance using earlier versions of the software update, which the FAA has accepted. American Airlines also sought to ensure that later-approved software versions would remain compliant with the AD, a request the FAA acknowledged as inherently covered by the directive’s language.
Boeing requested changes in terminology within the directive to more accurately describe the autothrottle behavior. The FAA agreed to some of these changes, opting to use “erroneous autothrottle behavior” instead of “throttle malfunction,” to provide a more precise description of the issue.
Cost of Compliance
The FAA estimates that the directive affects around 125 U.S.-registered Boeing 787 airplanes. The cost to comply involves installing and checking both the DCA and TM software updates, with estimated labor costs totaling $255 for the DCA software and $340 for the TM software per aircraft. Boeing has confirmed that there is no charge for the software itself, potentially reducing the financial impact on operators. Furthermore, some costs may be covered under warranty.
