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The cause of a few MiG-21 aircraft accidents in the Indian Air Force (IAF) has been attributed to engine failure due to jamming of the Reciprocating Slide Valve (RSV) of the engine fuel system resulting from possible contamination of fuel.
The engine of MiG-21 aircraft, which is made of numerous small and intricate components, some times develop problems at varying stages of exploitation under different environmental conditions. Once an accident takes place, the investigators of the accidents have to study the remnants of the components of the system to try and establish the cause of the failure. In cases of fighter crashes, the components are destroyed due to the high impact speed and intense fire in the wreckage. Therefore, it is not always possible to pinpoint the cause of the engine failure. However, in a few MiG-21 aircraft accidents, the problem of jamming of RSV has already been identified by investigators. The remedial measures could not be instituted till the investigators identified the cause.
Several steps are taken by the IAF on a continuous basis to augment flight safety. In this direction, the RSV has been modified in consultation with the designers of the equipment. Besides the use of one – micron filters during refueling of aircraft and maintaining high level of fuel discipline at Hindustan Aeronautics Limited (HAL) division and operating units have been instituted by the Indian Air Force. These measures have resulted in sharp reduction in the accident rate of the MiG-21 aircraft.
This information was given by the Defence Minister Shri AK Antony in a written reply to Shri Datta Meghe in Rajya Sabha today.
