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.
On the morning of 1 December 2021, a flight instructor was preparing for a proficiency check flight in a Diamond Aircraft Industries DA-40 aircraft at Moorabbin Airport, Victoria. While completing the daily inspection of the aircraft, the instructor identified an anomaly with one of the propellor blades. The painted surface surrounding the leading edge of the blade had cracked. In addition, an associated portion of the adhesively bonded metallic strip had partially detached from the blade body, approximately 5 cm from the propellor blade tip.
The instructor notified another more senior company pilot (also an instructor) of the defect. However, while discussing the problem, assurance was provided that company engineering was aware of the problem and that the aircraft was considered airworthy.
Preparations for the flight were subsequently completed. The instructor, along with the assessment pilot, departed Moorabbin Airport in the Diamond DA-40 for the proficiency check flight. About 20 minutes into the flight, and while operating in the designated training area, a metallic ‘ping’ was heard by both pilots along with the detection of an airframe vibration (that lasted 1 to 2 seconds). The instructor recalled no abnormality with the engine indications or flight controls. The proficiency check flight proceeded without further issue and concluded approximately 60 minutes later.
After the return landing at Moorabbin Airport, and during the post-flight inspection of the aircraft, the flight instructor identified damage to the previously inspected propellor blade (Figure 1). The bonded metallic erosion strip from the leading edge of the blade had detached and fractured.
Figure 1: The damaged propellor blade showing a fractured erosion strip along the leading edge (left) and impact damage to the leading edge (right)
The operator removed the propeller and submitted it to an overhaul facility for examination and repair. The engineering report identified that the propellor blade had sustained impact damage to the composite blade structure in the region of the partially missing metallic strip. The report concluded that the pre-existing impact damage was from runway debris which had compromised the adhesive bonding of the metallic strip, leading to its eventual failure.
Operator’s safety action
The operator’s investigation of this occurrence identified that, although the flight instructor had identified then reported the propellor damage to a senior company pilot, a communication error between the parties led to confusion regarding the nature of the defect. As a result, on 10 December 2021, the operator issued an advisory notice to their pilots stating:
- Crew, where possible and safe to do so, are to use their phones to take photos of any defects/concerns during an aircraft inspection.
- All concerns and supporting evidence are to be presented to the HAAMC or their delegate.
- Composite propellers tap tests are now conducted by the HAAMC and/or their delegate at the end of each flying day across the Diamond fleet.
This incident serves as a reminder to pilots of the importance of contacting appropriate maintenance engineering personnel if a defect is found during pre- or post-flight inspections. In this situation, although a propellor defect was identified that affected the airworthiness of the aircraft, company engineering personnel were not made aware of the damage. An inspection by a licensed engineer would have provided an opportunity to inspect and further assess to then make an appropriate decision regarding the seriousness of the damage.
Pilots, operators, and maintainers should note that it is a civil aviation regulatory requirement for all aircraft defects, whether major or minor, to be endorsed on Part 2 of the maintenance release. The maintenance release is a document considered central to the safe operation of an aircraft. The aircraft must not be flown if the defect or damage is assessed as major, and, if the defective/damaged item is required for the intended flight. The aircraft maintenance release ceases to be valid until such a defect is rectified.
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.