| 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 the morning of 28 August 2018, the crew of a Cessna 172S departed Tamworth, New South Wales (NSW) to conduct a training flight. There was an instructor and a student on board.
During cruise, while the student was flying and tracking towards Wakefield, NSW, the instructor noticed uncommanded control movement and pitching[1] of the aircraft. The instructor decided to observe the elevator[2] movement and saw that it was moving abnormally. The instructor took control of the aircraft to ascertain the integrity of the elevator and found that the aircraft was pitching without any pilot input.
Although the degree of movement was minor, the aircraft was not operating within prescribed performance parameters. The instructor performed further elevator control and trim checks and decided the best course of action was to conduct a return to Tamworth, NSW. The instructor contacted Air Traffic Control (ATC) to notify them of the control issues, and the aircraft was cleared to track direct to Tamworth. The instructor decided to land without flaps[3] to avoid exacerbating the control issues. The aircraft landed without incident.
Engineering inspection
Following the incident, the engineering inspection revealed that the elevator trim inspection panel had been partially installed causing an airflow disturbance over the right-hand elevator and trim.
Safety action
As a result of this incident, the maintenance organisation has advised the ATSB that they are taking the following ongoing safety actions:
- handover procedures to be reviewed and improved
- refresher training regarding the maintenance organisation exposition (MOE) procedures
- MOE procedures to be reviewed and updated
- more regular maintenance audits.
Safety message
This incident highlights the importance of ensuring that all pre-flight checks and procedures are carried out comprehensively and systematically. It also highlights the importance of ensuring that while the aircraft is in maintenance, all aircraft components are refitted and reinstalled in accordance with the aircraft’s maintenance manual and to verify the functionality of all critical aircraft components before returning it to service. The flight crew, in this instance, took all appropriate actions in-flight by assessing the situation, notifying ATC and conducting a return to the aerodrome resulting in a safe outcome.
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.
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- Pitching: the motion of an aircraft about its lateral (wingtip-to-wingtip) axis.
- Elevator: Elevators are flight control surfaces, usually at the rear of an aircraft, which control the aircraft's pitch, and therefore the angle of attack and the lift of the wing.
- Flaps: Flaps are a type of high-lift device used to increase the lift of an aircraft wing at a given airspeed. Flaps are usually mounted on the wing trailing edges of a fixed-wing aircraft. Flaps are used for extra lift on take-off. Flaps also cause an increase in drag, which can be beneficial during approach and landing, because it slows the aircraft.