A320 Flight Crew experiences ECAM for L/G Shock Absorber Fault at FL370; followed by Autopilot; Autothrottle; and FMA failures. Crew continues to destination for uneventful landing using manual flight and throttle controls.
Synopsis
A320 Flight Crew experiences ECAM for L/G Shock Absorber Fault at FL370; followed by Autopilot; Autothrottle; and FMA failures. Crew continues to destination for uneventful landing using manual flight and throttle controls.
Narrative
In cruise at FL370 approximately 300nm from destination and four hours into the flight we received a ECAM for L/G -Shock Absorber Fault. We then received ECAM for A/P and A/thr. We then noticed the engines had rolled back to idle. The Captain (PF) then backed the throttles out of climb detent to regain control. We also noticed that we lost both Flight Directors and FMA's. Initiated a call to Dispatch to help establish contact with Maintenance. As we were talking to Maintenance (About 10 minutes later) we noticed that the Flight Directors reappeared on both of our PFD's. We then attempted to engage the autopilot and autothrottle. This worked for less then a minute then we received the L/G shock absorber ECAM again followed by the A/P and A/thr disconnect ECAM's. At this point we decided we would not use the Auto Flight systems for the remainder of the flight. Since there is nothing in the Flight Manual about this situation we consulted Maintenance for any other information we would need to know to conduct a safe approach and landing. They informed us that to be alert for an ECAM for the N/W which we had already noted in the flight manual. In coordination with Dispatch we declared an emergency and the Captain flew an uneventful ILS approach to landing.
Second reporter narrative
Uneventful until about 2 hrs into flight... Received Anti Ice Stby Pitot ECAM. Worked to clear and ECAMS complete; screens normal. About 4 hrs into flight... At FL370 received L/G Shock Absorber Fault; AP and ATHR kicked off; throttles went to idle thrust. Immediately followed by Auto FLT AP OFF; Auto FLT A/Thr off ECAM. Lost all FMA's and both F/D. Attempted to restore Autoflight; but would not engage. Discussion with Dispatch and Maintenance were inconclusive about actual system fault determination. Upon reviewing FM; further notes; warnings and cautions revealed possible nosewheel offset upon landing. Dispatch was coming to same consideration upon review of FM; and had already notified Tower to standby with equipment upon landing. Flew manual and raw data approach to an uneventful landing.
NASA callback
The reporter believes that a sensor failure caused the reported anomalies although no definitive cause was reported by Maintenance. He also states that Autothrust did not reduce thrust during the second failure; indicating Thrust Lock and maintaining the current thrust setting. He believes that the first instance was the same except that Autothrust had just made a large thrust reduction at the moment of failure; giving the appearance of a failure caused thrust rollback.
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Source: NASA Aviation Safety Reporting System (public domain). Reports are voluntary submissions and are not verified by NASA.