Singaporean F-16 crash caused by rare failure

A RSAF F-16C is seen here taxiing. These aircraft are undergoing a comprehensive upgrade programme which will, among other additions, add a new radar to the aircraft. (Luhai Wong)

Singapore’s Ministry of Defence (MINDEF) announced on 19 June that it has concluded its investigation on the Republic of Singapore Air Force (RSAF) F-16 crash at the western Tengah Air Base earlier in May.

According to MINDEF, data downloaded from the flight data recorder and digital flight control computer of crashed aircraft were reviewed along with its maintenance records and procedures. The pilot and aircraft engineers were also interviewed. MINDEF added that the effort was supported by aircraft manufacturer Lockheed Martin and the Transport Safety Investigation Bureau.

“The root cause of the malfunction has been attributed to degraded pitch rate gyroscopes, which form part of the motion sensors feeding inputs to the Digital Flight Control Computer,” stated MINDEF.

“Specifically, two out of four pitch rate gyroscopes in the F-16 gave erroneous but similar inputs to the Digital Flight Control Computer,” it explained. “This resulted in the flight control logic accepting the similar erroneous inputs as “correct”, and sequentially rejecting the inputs from each of the remaining functioning gyroscopes as “incorrect”.”

As a result, the computer manoeuvred the aircraft in response to the erroneous pitch rate feedback signal from the two degraded gyroscopes, causing a loss of control for the pilot. According to Lockheed Martin, this is first such failure reported to the company since the F-16 first flew in 1974.

MINDEF announced in 2015 that the aircraft fleet will undergo a comprehensive mid-life upgrade (MLU) programme, with key enhancements centred on a new active electronically scanned array (AESA) radar – likely the Northrop Grumman’s AN/APG-83 Scalable Agile Beam Radar – and updated avionics including the Link-16 Multifunctional Information Distribution System-Low Volume Terminals (MIDS-LVT) which would enable the F-16s to share and receive data more readily with the newer F-15SG aircraft.

Upgrade work commenced in 2016 and is expected to be completed by around 2023, with the F-16 fleet remaining operational until the 2030s after which it will be replaced by an undisclosed number of F-35s. The status of the upgrade work has yet to be updated by MINDEF.

by Jr Ng