Spanair MD-82 crash inquiry battles to understand absent flap warning
By David Kaminski-Morrow
Investigators of the Spanair Boeing MD-82 crash in Madrid are set to recommend a mandatory check of configuration warnings on the type, after confirming that the jet's flaps had not been deployed prior to a second attempt at take-off.
Spain's Comision de Investigacion de Accidentes e Incidentes de Aviacion Civil, in a draft report, states that the cockpit-voice recorder of flight JK5022 to Las Palmas did "not record any sound" from the take-off configuration warning system on the aircraft.
This initial report into the 20 August accident states that the crew did deploy the flaps to an 11° position when the aircraft first left its gate at Madrid Barajas.
But after receiving departure clearance the crew opted to taxi back to the apron after reporting a technical fault with the ram air temperature probe. The probe had apparently heated to 105°C while the aircraft was still on the ground.
Electrical circuits normally supply heat to the probe only when the aircraft is airborne - this is determined by logic circuits using weight-on-wheels sensors in the nose-gear. The reason for the apparent logic mismatch remains under investigation.
Crucially the probe shares an electrical link with the configuration-warning system, as well as other functions on the aircraft, through a relay designated R2-5.
After the MD-82 returned to the apron to have the temperature probe checked, engineers reportedly disconnected a circuit-breaker in order to resolve the heating issue before clearing the flight to depart
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