4th of January 1991

British Airways Concorde, G-BOAE, was operating a scheduled flight between London Heathrow Airport, England and JF Kennedy Airport New York, USA on this day in aviation history. After departing London Heathrow at 10.55 utc the aircraft climbed to each (initial) cruise flight level (FL 560) and accelerated to its cruise speed of Mach 2.0.

Concorde (from public domain)

At 12.07 utc when the aircraft was at the approximate longitude 27 West (~1/3 into the Atlantic crossing) an engine appeared to surge. A vibration was felt by the crew for a very short time (estimated by the crew to last 0.5 to 1 seconds). A check of the engine parameters by the crew did not reveal anything abnormal. The crew pressed the event marker button shortly after the occurrence, this placed a time marker on the Flight Data Recorder (FDR) data. This would assist engineers in investigating the suspected engine surge. The cruise phase of the flight continued without further incident toward the east coast of the USA. During the descent at a speed of Mach 1.1 at flight level 410 another abnormal vibration was felt, this time lasting longer, estimated to be approximately 10 seconds. Again the event marker button was pushed, the time stamp at this event marker was 14.03 utc. The flight continued normally without further vibrations being felt and a normal landing at New York was carried out.

During the post-flight inspection of the aircraft, a piece of the rudder was missing. A detailed examination followed and it was found that a portion of the lower rudder was missing, together with most of the skin on the right side above the Powered Flying Control Unit (PFCU) attachment structure. Some light damage was also found on the tailcone immediately below the rudder. The lower rudder was removed from the aircraft and shipped to the UK for examination and investigation. A readout of the Flight Data Recorder Upper & Lower Rudder revealed no signs of engine stalls, (Source; www.concordesst.com)

it was suspected that the vibrations were caused by the structural failure of the rudder.

The remaining part of the lower rudder after removal from G-BOAE

The detailed investigation that followed into the structural failure revealed that maintenance on the rudder at shop-level contributed to water ingress into the rudder which led to the structural failure. An extensive report detailing the findings of the investigation is available by clicking here.