What happened
On June 7, 2010, an Embraer ERJ 170-100 LR departed from Münster/Osnabrück airport for a scheduled flight to Frankfurt/Main. The aircraft was carrying 54 passengers and four crew members. Shortly after takeoff, the pilot attempted to retract the landing gear, at which point the co-pilot noticed that the right main landing gear had not retracted correctly. This was followed by a visual and audible "LG LEVER DISAG" warning in the cockpit.
While the crew was following the abnormal landing gear extension checklist, a second warning, "HYD 2 LO PRESS," appeared on the display. After successfully completing the necessary procedures, the crew confirmed the gear was locked and down. The crew decided to continue the flight at 12,000 feet and 230 knots, intending to perform a precautionary landing in Frankfurt/Main. No emergency was declared, and the crew conducted an extensive briefing regarding the expected landing conditions. The aircraft landed at Frankfurt/Main at 10:54 local time. Upon exiting the runway, the aircraft sustained heavy damage to the landing gear components and wing structure, though there were no injuries to the passengers or crew.
The investigation
The BFU investigation focused on the structural integrity of the landing gear components and the maintenance history of the aircraft. Investigators examined the damage to the right wing, where the support fitting for the right main landing gear actuator had broken away, causing a piece of rib 6 to be torn out. The hydraulic cylinder of the actuator had subsequently punctured rib 4A. The investigation also identified fatigue cracks in the support fitting of the left main landing gear.
Review of the aircraft's maintenance records revealed that a manufacturer Service Bulletin (SB 170-57-0008) existed, which recommended replacing the support fitting with a modified version by the 5,000th flight cycle to prevent fatigue cracks. The aircraft in question had completed 8,641 landings, significantly exceeding the recommended limit.
Findings
- The primary cause of the incident was the fatigue failure of the right main landing gear actuator support fitting.
- The failure of the fitting caused secondary damage, including the breakage of wing rib 6 and the piercing of rib 4A by the hydraulic cylinder.
- The aircraft had exceeded the manufacturer's recommended replacement interval for the component by over 3,600 flight cycles.
- While the manufacturer had issued a Service Bulletin for the replacement, the regulatory authority had not issued a mandatory Airworthiness Directive (AD), leaving the implementation of the fix to the discretion of the operator.