Indonesian investigators have concluded that a fractured water-spray deflector prevented the nose-gear of a Boeing MD-90 deploying before the aircraft landed at Batam.
The crew had received a nose-gear warning on the instrument panel as the Lion Air aircraft (PK-LIO) climbed out of Medan on 23 February 2009.
Having recycled the landing-gear three times the pilots were given an indication that the undercarriage was retracted and locked, and opted to continue to Batam.
But during the final approach to the airport the crew received another nose-gear warning and executed a go-around. The jet held for nearly 90min at 2,400ft while the pilots addressed the problem.
Despite "many" attempts to extend the landing-gear, says the Indonesian National Transportation Safety Committee, the red warning indicator remained illuminated, and the crew decided to conduct an approach to runway 04 without the nose-gear deployed.
Emergency vehicles laid foam on the runway to minimise the risk of fire and the aircraft - carrying 156 passengers and six crew - touched down, and came to a halt, with the nose-gear retracted. None of the occupants was injured.
Preliminary inquiries discovered that the water deflector on the nose-gear had broken, jamming the nose wheel in the retracted position.
"The investigation is continuing and will include the operational procedures used during the flight to address the landing gear malfunction, and analysis of the mode of failure of the nose landing-gear spray deflector," the NTSC says.
It says there was no mandated inspection period for the deflector on the 13-year old twinjet. The MD-90 had conducted 15,475 cycles and undergone a C-check seven months earlier.
NTSC points out that the ground clearance of the deflector is "quite low" and that taxiing could result in damage to the attachment point.