Proof of the cause of last year's Ilyushin Il-86 crash at Moscow will never be found, says the accident investigators' final report, but it contains recommendations about pilot training and stabiliser control design. The horizontal stabiliser was found at maximum nose-up pitch in the wreckage when the Pulkovo Airlines aircraft stalled just after take-off from Moscow Sheremetyevo on 28 July 2002.
The flight data recorder (FDR) showed that the stabiliser began to increase in pitch 2s after take-off, and it did not stop increasing until it had reached maximum nose-up pitch. Investigators say they do not know whether the cause was continuous crew selection of nose-up trim or some kind of malfunction.
They describe malfunction as improbable, reporting that all four stabiliser actuators were found to be serviceable, and they know from the cockpit voice recorder and the FDR that the crew did not appear to have recognised the developing stabiliser situation nor to have attempted to counteract it except with the elevator, which is not sufficiently powerful on its own.
The post-crash fire was so severe, however, it destroyed any conclusive proof about whether the cockpit stabiliser switches were faulty.
Source: Flight International
