RSAF F-16 crash at Tengah Air Base was due to component malfunction; fleet to resume flying

SINGAPORE: The crash of a Singapore F-16 jet at Tengah Air Base last week was due to a malfunction of a component known as pitch rate gyroscopes, the Ministry of Defence (MINDEF) said on Saturday (May 18).

"The flight data recorder recovered from the crashed F-16 showed that its pitch rate gyroscopes gave erroneous inputs to the flight control computer. This led to the pilot being unable to control the plane at take-off," MINDEF said in a media release.

The ministry said that the simultaneous failure of the gyroscopes seen in the May 8 incident "is a very rare occurrence", adding that this is the first such malfunction in the Republic of Singapore Air Force's (RSAF) entire F-16 fleet.

Pitch rate gyroscopes are sensors that a flight control computer uses to control an aircraft, former RSAF pilot Ong Swee Chuan told CNA on Sunday.

The gyroscopes are used to measure the aircraft's pitch rate, which is the rate at which the aircraft's nose goes up or down, he added.

All F-16 fighter jets are fitted with four such gyroscopes.

At any one time, three pitch rate gyroscopes are used and the average of two is taken to provide data to the flight control computer, said Mr Ong.

"For this incident, I think there are two that simultaneously were at fault," Mr Ong added.

When two of the three gyroscopes in use are faulty, the one giving the correct data will be "voted out" because the computer assesses that the odd one out is providing incorrect data, he said.

The spare fourth gyroscope, which will then be asked to provide its data, will also be "voted out" because its data is not in sync with the two faulty ones.

This makes the aircraft almost uncontrollable, Mr Ong added.

With the cause of the crash now identified, MINDEF said that Singapore's F-16 fleet will resume flying.

"But as an added precaution, each F-16 pitch rate gyroscope will be checked and cleared before resumption of flights," it added.

F-16 training was temporarily suspended in the wake of the incident at Tengah Air Base. The fighter jet crashed shortly after taking off at about 12.35pm. The pilot successfully ejected from the aircraft and did not suffer major injuries.

The RSAF, together with manufacturer Lockheed Martin, will conduct further studies to determine the specific causes of the gyroscope malfunction that resulted in the crash at Tengah Air Base.

Singapore's F-16s have been in service since 1998. They were recently given a mid-life upgrade but would have to retire after the mid-2030s.

The country had identified the F-35 family of jets as a replacement. 

In February, it announced that it would buy eight F-35A jets, adding to an earlier order of 12 F-35 jets of the “B” variant