Cessna 310R, VH-COQ, Groote Eylandt Aerodrome, on 25 March 2003

The damage to the rod end was consistent with failure during the retraction of the landing gear after take-off at Gove. Disconnection of the left main gear from its push-pull tube meant that the gearbox was unable to extend or retract that gear. It also meant that the emergency gear extension was ineffective. Fatigue cracking within the rod eye section was the principal factor behind the separation of the push-pull tube and the subsequent failure of the landing gear to operate correctly.

The investigation was unable to determine why the rod end failed. It is possible that an increase in transmitted loads resulting from excessive system friction, system rigging problems or the failure of interrelated components could have contributed to the initiation of the rod end cracking.

The pilot was confronted with the high workload of maintaining control during night circuits and trouble shooting a landing gear malfunction. The night conditions meant that people on the ground were of limited help, at least initially, in determining the status of the landing gear. Landing the aircraft with the gear retracted allowed for some directional control during the landing slide and probably limited damage to the aircraft.

The release of the emergency exit on final approach had the potential to inflict serious damage to the tailplane with possible control problems resulting.

The pilot of a Cessna 310R made a night departure from Gove, NT, at 1900 Central Standard Time for Groote Eylandt, NT. After take-off he noticed two unusual thumps near the end of the landing gear retraction cycle. Normal landing gear up indications were observed and there were no unusual handling characteristics during the flight to Groote Eylandt.

The pilot reported that on arrival in the circuit area he selected the landing gear down. The landing gear operated but the left main landing gear down light did not illuminate at the end of the cycle. The pilot changed the down light bulb without change to the indication. He then cycled the landing gear by selecting up then down, which resulted in the left main and nose landing gear down lights not illuminating. The pilot spoke to ground personnel by radio and made a few low passes along the runway to allow them to observe and report on the condition and position of the landing gear. However, they were unable to see the position of the landing gear due to the darkness.

The pilot manoeuvred the aircraft in an unsuccessful attempt to free the landing gear. Further cycling of the landing gear and a manual landing gear extension were attempted without success. Emergency services, notified by air traffic services, attended and were able to provide enough illumination of the aircraft for observers to report that the nose gear was not extended, the left main gear was at an angle and the right gear appeared to be in the down position.

After consultation with a pilot on the ground and briefing the passengers, the pilot made an approach to runway 28 with the gear selected up and the flaps down. While on final approach the pilot unlatched the emergency exit and cabin door. The emergency exit, which consisted of the pilot's side window and associated frame, detached from the aircraft.

The aircraft made a smooth touchdown and slid on the runway. The pilot selected the mixture control to idle cut off and the fuel, magnetos, alternators and battery to off. The passengers exited through the cabin door and over the right wing and moved away from the aircraft. There was no fire, but the propellers and the underbelly of the aircraft were damaged.

Inspection of the aircraft by engineering personnel revealed that the rod end on the outer end of the left main gear inboard push-pull tube had separated, effectively disconnecting the left main landing gear assembly from the actuating mechanism.

Laboratory examination by the ATSB revealed that rod end separation had occurred under predominantly tensile forces after fracturing through one side of the eye section. Detailed examination of the fracture surfaces found characteristic evidence of fatigue cracking, originating from the outer corners of an integral lubrication port within the eye body. The examination found no evidence of any material or manufacturing defects having contributed to the failure.

There were no reports of previous landing gear problems.

The electro-mechanical landing gear system utilised a gearbox, driven by an electric motor, to turn two bellcranks that extended or retracted a push-pull tube to each landing gear assembly. A landing gear hand-crank provided an alternative manual means to drive the gearbox.

In the sub-section titled `EMERGENCY LANDING PROCEDURES', the Cessna 310R pilot's operating handbook (POH) specified unlatching of the cabin door prior to flare-out. However, there was no reference to in-flight unlatching of the emergency exit in any of the emergency checklists.