2010 Embraer ERJ 170-100 LR Landing Gear Incident at Frankfurt/Main

Incident Overview and Flight Details On 7 June 2010, a commercial Embraer ERJ 170-100 LR aircraft departed from Münster/Osnabrück Airport at 10:12 local time. The flight was operated by a German airline and carried four crew members and 54 passengers. Shortly after takeoff, the pilot initiated the landing gear retraction sequence. The copilot observed that the right main landing gear did not retract properly. The cockpit crew subsequently received a visual and then an aural warning message, “LG LEVER DISAG,” on the display. The crew addressed the warning in accordance with the “ABNORMAL LANDING GEAR EXTENSION” checklist. Following this procedure, the landing gear was fully extended and locked, as confirmed by three green indicators on the display. During the handling of the warning, a caution message, “HYD 2 LO PRESS,” appeared on the display. The crew addressed this issue according to the applicable checklist. The crew then decided to continue the flight at flight level 120 at 230 knots and to make a precautionary landing at Frankfurt/Main Airport. No emergency was declared. Before commencing the descent, the crew conducted an extensive briefing regarding the expected approach and landing under the prevailing conditions. The aircraft landed at Frankfurt/Main at 10:54 local time with the anticipated technical limitations, including the failure of the inner brakes and nose wheel steering. After leaving the runway, the landing gear was inspected by the airport fire brigade. The aircraft was subsequently towed to a parking position. ## Aircraft and Damage The aircraft was an Embraer ERJ 170-100 LR, a low-wing monoplane with retractable landing gear in a tricycle configuration. It was powered by two General Electric CF34-8E5 turbofan engines. The maximum takeoff weight was 37,200 kg. The aircraft, with serial number 17000006, was built in 2002 and had a total operating time of 9,130 hours and 8,641 landings. It was registered in Germany and operated by a German airline. The damage found on the aircraft included a broken support fitting for the right main landing gear retraction actuator, along with a portion of rib 6, in the right wing. The hydraulic cylinder of the actuator had penetrated rib 4A. The retraction actuator cylinder was externally damaged, as were the connected hydraulic hoses. The attachment eye of the unlocking actuator was torn out, and its piston rod was bent. The locking strut of the right landing gear was bent. The support fitting for the left main landing gear retraction actuator showed two cracks in the upper area of the connection to rib 7. Both the broken support fitting in the right wing and the cracks in the left wing support fitting were fatigue failures. ## Investigation Findings and Safety Recommendations The investigation determined that the right main landing gear retraction actuator support fitting had failed due to a fatigue fracture. This failure caused a piece of rib 6 to break out, and the hydraulic cylinder of the actuator then penetrated rib 4A. The manufacturer had previously identified this failure mode in its own fatigue tests and described it in Service Bulletin 170-57-0008. The bulletin recommended replacing the support fitting with a modified part by the 5,000th flight. However, the affected aircraft had completed 8,641 flights before the incident. The BFU issued safety recommendations to the Brazilian aviation authority, ANAC, which is responsible for the type certificate of the aircraft. Recommendation 16/2010 advised ANAC to ground the aircraft identified in Service Bulletin 170-57-0008 and initiate an inspection for cracks in the support fitting and pins before the next flight. Recommendation 17/2010 advised ANAC to upgrade the service bulletin to an Airworthiness Directive. The implementation of the service bulletin on the remaining four affected aircraft was considered to have addressed the safety recommendations, and the upgrade to an Airworthiness Directive was no longer necessary as there were no remaining aircraft to which it would apply.