A Sling aircraft’s brake disc was severely corroded before it fractured after landing at Moorabbin Airport, an ATSB investigation has found.
The two-seat light aircraft, operated by Learn to Fly Australia, was being used for a training flight with an instructor and student pilot on board out of Melbourne’s Moorabbin Airport on 14 February this year.
After landing on runway 17R and vacating the runway via taxiway A4, there was a jolt and an unusual sound from the right side of the aircraft.
The instructor continued to taxi, and after noticing that the aircraft’s wheel brakes were less effective, brought the aircraft to a stop and conducted after-landing checks without noting anything significant.
After then taxiing to the operator’s parking area and exiting the aircraft, the instructor saw the right main landing gear brake disc had failed.
“The ATSB’s examination of the brake disc identified severe corrosion had compromised its structural integrity to the point where it failed during normal braking after landing,” ATSB Director of Transport Safety Dr Stuart Godley said.
“This corrosion was not identified by those maintaining and operating the aircraft as having progressed to a point where failure of the brake disc was possible.”
The investigation report notes the operator parked its aircraft on concrete pads in the open at Moorabbin Airport, which is about 3km away from Port Phillip Bay.
“Being parked outside and operated in the vicinity of a saltwater environment would have contributed to the corrosion development,” Dr Godley noted.
“The effect of the environment was also demonstrated by the extent of corrosion observed on the brake disc assemblies of the other 6 aircraft in the operator's fleet.”
The aircraft had been fitted with an unapproved aftermarket brake disc.
“As there was no record in the aircraft logbooks of fitment of the brake disc, the time taken for the corrosion to develop could not be established,” Dr Godley noted.
“However, there were multiple opportunities to intervene ahead of the failure, given that the aircraft was being inspected daily by pilots, and typically every 2 months by a maintenance organisation,” Dr Godley said.
“Importantly, the maintenance organisation was aware of the corrosion, but had not identified that it had progressed to a point where the structural integrity of the brake disc had been compromised, or taken any maintenance actions to limit its progression.”
The operator has subsequently replaced all corroded brake discs fitted to its entire Sling fleet with approved parts, and has amended its procedures to move aircraft onto the apron prior to boarding to allow for easier access to inspect landing gear.
“Aircraft brake system failures can result in serious outcomes such as a runway excursion or a taxiing collision,” Dr Godley noted.
“As such aircraft operators and maintainers should take timely action to prevent the progression of corrosion, and replace parts before the serviceability of an aircraft is affected,” he said.
“Operators should also give consideration to their aircraft operating environments, and whether additional maintenance can be undertaken to limit corrosion development.”
Read the final report: Wheel brake failure involving Sling Aircraft Sling LSA, VH-PPY, Moorabbin Airport, Victoria, on 14 February 2025