| Occurrence Briefs are concise reports that detail the facts surrounding a transport safety occurrence, as received in the initial notification and any follow-up enquiries. They provide an opportunity to share safety messages in the absence of an investigation. |
What happened
On 23 February 2018, at about 0933 Western Standard Time (WST), a Piper Aircraft Corp PA-44-180 was conducting a training flight from Jandakot Airport, Western Australia (WA) to Rottnest Island Airport, WA with two crew members on board.
During the approach to Rottnest Island, the landing gear was extended. The gear unsafe light illuminated during the extension process and turned off when the left and nose gear lights turned green to indicate they were locked, however, the right gear light did not illuminate. The crew conducted a missed approach and began to troubleshoot the issue during the return flight to Jandakot.
On approach to Jandakot, the crew followed the emergency gear extension procedure. The light for the right-hand gear did not illuminate to indicate the landing gear had locked, however the gear unsafe light remained off.
The crew requested a fly-by of the tower for a visual inspection of the landing gear. Air Traffic Control (ATC) reported that all three wheels appeared down, with no differences between left and right observed.
The crew requested emergency services to be on standby and once confirmed, made their final approach. On landing, the right landing gear collapsed, and the aircraft came to a stop to the right of the runway, at 90 degrees. ATC activated the crash alarm and full emergency procedures were conducted. The crew disembarked the aircraft unharmed.
Engineering inspection
Following the incident, inspection of the right-hand landing gear revealed that the gear actuator seals were not correctly functioning and that the pivots on the down lock mechanism were stiff. The faulty seals resulted in a loss of actuator pressure in the down position. When emergency procedures were followed for gear extension, the gear could not free fall and lock into position due to the resistance at the pivot. It was noted that retraction and free fall of the landing gear was tested during maintenance in November 2017 with no non-normal indications. However, the aircraft was not returned to service until February 2018, during which time it is suspected that the pivots became stiff.
Repairs to the aircraft were carried out in accordance with the aircraft maintenance manual to:
- reseal the actuator with new O-rings
- replace the down lock springs
- dismantle, grease and reassemble the down locks.
Testing of the landing gear was conducted, and the aircraft was returned to service.
Safety message
Where an aircraft has been out of service for an extended period of time, it is important to verify the functionality of all critical aircraft components before returning it to service. These checks should be conducted in addition to the routine, pre-flight checks.
It is important that pilots remain aware that despite conducting comprehensive pre-flight checks, unanticipated failures can still occur during flight. In this situation, the flight crew took all possible precautions prior to landing by:
- following non-normal procedures
- conducting additional checks to assess the situation
- providing clear communications to ATC.
About this report
Decisions regarding whether to conduct an investigation, and the scope of an investigation, are based on many factors, including the level of safety benefit likely to be obtained from an investigation. For this occurrence, no investigation has been conducted and the ATSB did not verify the accuracy of the information. A brief description has been written using information supplied in the notification and any follow-up information in order to produce a short summary report, and allow for greater industry awareness of potential safety issues and possible safety actions.