What happened
On 17 May 2017, a Cessna 525A, registration N525DT, was performing a private flight when it approached Runway 27 at Gloucestershire Airport using ILS/DME procedures. At the time of the approach, the pilot noted rainy conditions with broken cloud layers at 500 ft, a visibility of 5,000 metres, and a temperature of 13°C. A runway inspection performed shortly before the arrival had identified a wet surface with patches of standing water.
Upon touchdown, the pilot found that the aircraft's brakes were not functioning. To avoid remaining on the active runway, the pilot steered the aircraft onto a grassy area to the right of the runway, where the aircraft eventually stopped. The incident resulted in no injuries to the two persons on board, though the aircraft sustained minor damage to the right flap and the right main landing gear door.
The investigation
Investigators examined the aircraft's braking system following the report of the malfunction. During subsequent engineering inspections, technicians were unable to recreate the reported failure of the brakes. Despite the inability to replicate the fault, maintenance teams performed a precautionary check of the brake cable rigging and proceeded to replace both the anti-skid computer and the brake metering valve.