History of the Flight
On 11 May 2024, an Embraer ERJ170 (registration F-HBXI) operated by HOP! departed Paris Charles de Gaulle at 12:15 UTC for a chartered passenger flight to Toulouse-Blagnac. At 13:11, while established on the ILS for runway 14R at approximately 2,500 ft, the pilot monitoring (PM) selected the landing gear control lever to DOWN. The left main landing gear transit light remained illuminated, and the LANDING GEAR aural warning activated, followed by an EICAS message indicating LG LEVER DISAG. The crew attempted a landing gear retraction and extension sequence, but the left main landing gear did not lock. They performed a missed approach, retracted the gear and flaps, and climbed to 4,000 ft.
At 13:14, the PM initiated the LG LEVER DISAG emergency procedure, which led to the ABNORMAL LANDING GEAR EXTENSION procedure and subsequently the PARTIAL OR GEAR UP LANDING procedure. The captain informed the cabin crew of the situation. The PF informed the controller, requesting assistance upon arrival. The controller offered to observe the landing gear with binoculars. The crew prepared for another ILS approach to runway 14R. At 13:22, the captain took over as PF. The controller asked if they wanted a low pass for observation, but the crew declined, asking the controller to observe the gear position. At 13:26:49, the autopilot was deactivated. Shortly after, the controller reported seeing both main landing gear extended. At 13:28:39, the aircraft touched down on runway 14R. During deceleration, the PM informed the controller that everything appeared normal from the cockpit, and they would continue taxiing to avoid blocking the runway. The controller advised they could stop on the runway. After stopping, the crew shut down engine 1 for inspection. Firefighters reported no anomaly. After restarting engine 1, the PF could not steer the aircraft. The crew then started the APU and shut down both engines. A mechanic reported a mechanical rupture on the left main landing gear; the locking-stay was out of position. All occupants disembarked via stairs at 14:40 without incident. The aircraft remained on the runway until the next day.
Aircraft Information
The left main landing gear locking-stay bracket had separated from the landing gear shock strut. The four attaching bolts were examined:
- Rear top position: screw broken without deformation; all components recovered.
- Forward top position: screw broken and bent; washer missing.
- Rear bottom position: screw in good condition; washer and nut missing; cotter pin fragment in place; metal debris in threads.
- Forward bottom position: screw in good condition; washer and nut missing; cotter pin fragment in place; metal debris in threads.
A scanning electron microscope examination of the rear top screw revealed micro-striations characteristic of fatigue cracking under repeated tensile loads. The forward top screw showed sudden failure from bending overload. The top nuts were type MS14145. The bottom screws had traces of green product and debris indicating MS17826 nuts had been installed. The maximum tightening torque for MS17826 nuts is 8 Nm, but the Liebherr documentation specified 22 to 25 Nm. It is very likely that the incorrectly sized bottom nuts were damaged during installation and subsequently tore off. The forward top bolt then cracked from fatigue and broke, leaving the bracket held only by the rear bolt, which then failed from overload.
Meteorological and Airport Information
At 13:30, the METAR reported a southeasterly wind of 10 kt, CAVOK, temperature 27°C, QNH 1015 hPa. Toulouse-Blagnac has two parallel runways 14/32: 14R/32L is 3,503 m × 45 m, and 14L/32R is 3,025 m × 45 m.
Examination of Cockpit Circuit Breaker Panels
Circuit breakers accessible to flight crew are located on left and right cockpit consoles. Each pilot cannot see the other's actions on the opposite panel from their seat.