What happened
On 7 June 2021, an ERJ 170-100 LR, registration G-CIXW, was conducting a commercial passenger flight from Gibraltar to Birmingham Airport. During the descent from FL3-80, the crew received a pitch trim fail alert on the Engine Indication and Crew Alerting System (EICAS). To mitigate the risk of a potential pitch trim runaway, the pilot flying (PF) disconnected the autopilot, which subsequently failed.
As the aircraft approached runway 15 at Birmingham, the crew identified that both primary and secondary trim systems were non-functional. This resulted in significantly higher nose-down control forces than usual. To manage the flight path, the crew implemented a strategy where the PF used both hands on the yoke to maintain pitch control, while the pilot monitoring (PM) managed the throttles via the autothrottle. Despite the increased physical effort required, the aircraft maintained a stable approach and landed safely.
Upon touchdown, a separate steering failure alert illuminated. The loss of the steering system prevented normal nosewheel control, forcing the commander to use differential braking and asymmetric engine power to taxi the aircraft to the stand.
The investigation
The AAIB examined the aircraft's maintenance history, flight data, and manufacturer feedback. The investigation focused on why the pitch trim system became inoperative and the cause of the subsequent steering malfunction. Technical analysis of the horizontal stabiliser actuator control electronics unit (HS-ACE) revealed a failure in one of its channels.
Flight data monitoring (FDM) confirmed that while the aircraft was speed stable and remained within the glideslope, the pilot had to compensate for the lack of trim by applying larger-than-normal pitch inputs. The investigation also reviewed the operator's lubrication schedule for the horizontal stabiliser, noting that the aircraft had been lubricated in accordance with manufacturer intervals.