An E190 airliner had a slat failure on approach to Launceston, Tasmania, after a torque tube was incorrectly installed during recent maintenance, an ATSB investigation report details.
On 15 April 2025, the Alliance Airlines-operated Embraer E190 was commencing approach to Launceston when the flight crew observed multiple caution messages, including a slat failure.
After actioning relevant checklists, the flight crew opted to divert to Melbourne Airport, the longest available runway in the region, and conducted a flapless landing without further incident.
A post-flight inspection found one of the torque tubes in the left wing’s slat system had disconnected, because the locking bolt designed to secure it to the actuator had not been correctly fitted.
The error was tracked to a scheduled task carried out when the aircraft was under maintenance between November 2024 and March 2025. The aircraft flew 50 post-maintenance flights before the incident.
A similar occurrence involving another Alliance E190 was also identified, where a torque tube in the left wing’s flap drive system had disconnected after it was incorrectly assembled when it was last refitted.
“In both occurrences the locking bolts that secured the torque tubes to their actuators had not been fitted correctly into the holes of the splined shafts, since the torque tubes had been incorrectly positioned during installation,” ATSB Director of Transport Safety Dr Stuart Godley explained.
“In both occurrences, those carrying out and those certifying the torque tube installations did not identify that they had been incorrectly assembled before the aircraft were released back into service.”
Aircraft manufacturer Embraer reported five similar occurrences relating to incorrect torque tube installation involving E170, E175 and E190 aircraft (which share similar componentry) between 2005 and 2011.
Embraer subsequently made amendments to the aircraft maintenance manual to reduce the possibility of assembly errors, with changes communicated in multiple documents available to operators and maintainers of E190s.
“Historical occurrence and technical information provide an opportunity to review known errors prior to commencing particular maintenance activities,” Dr Godley said.
“Information on previous errors can be available from multiple sources including the manufacturer, national aviation authorities, accident investigation authorities, and within operators’ safety management systems.”
As a result of its two occurrences, Alliance Airlines issued a maintenance notice, detailing both incidents and reiterating the aircraft maintenance manual information for the correct installation of flap and slat torque tubes.
The maintenance organisation added an additional task card, which is automatically issued when work is scheduled on the E190 slat system torque tubes, to provide guidance in addition to the aircraft maintenance manual.
Read the final report: Flight control event involving Embraer E190, VH-UZD, 29 km south-east of Launceston Airport, Tasmania, on 15 April 2025