THE Defence Force has grounded its fleet of Hercules C-130 transport aircraft after an "unusual" fault prompted an emergency landing.
The fault was detected on Monday night during a training flight near Richmond, north-west of Sydney, a Defence spokeswoman told Fairfax newspapers.
Following the incident, all 24 of the RAAF's Hercules planes were grounded for all non-essential flights until the cause had been detected.
Defence said a plane had declared an emergency on Monday about 8.25pm (AEST) after its crew detected a fault with the nose-wheel.
At 8.55pm the crew put in a mayday call but landed safely at the Richmond Base 20 minutes later