14.3 Airworthiness, Serviceability and Defect Reporting

Airworthiness Applies to Drones Too

Candidates sometimes assume airworthiness is a crewed-aviation concept. It is not. Section 20AA(4) of the Civil Aviation Act 1988 applies to all Australian aircraft, RPA included. It provides that an owner, operator, hirer or pilot must not commence a flight, or permit a flight to commence, if any of the following apply:

• there is an outstanding requirement imposed by or under the regulations in relation to maintenance of the aircraft;
• the aircraft will require maintenance before the flight can end; or
• there is a defect or damage that may endanger the safety of the aircraft, or of any person or property.

That is the legal frame. Everything else in this section is about how a remote pilot satisfies themselves that none of the three applies.

Who Is Responsible

The MC's functions and duties are set out in AC 101-05, and for RPA above a certain weight CASA assesses the MC's suitability directly.

Certificates of airworthiness

Most RPA do not hold a certificate of airworthiness. Large RPA (more than 150 kg) are the exception: under CASR 101.255(1) they require either an experimental certificate or a restricted-category certificate of airworthiness, issued under Subpart 21.H, before they may be operated.

Determining Serviceability for a Specific Operation

Schedule 4 topic 3(a) asks the pilot to determine RPAS serviceability for a specific operation — and the phrase "for a specific operation" is doing real work. Serviceability is not a binary property of the aircraft; it is a judgement about whether this aircraft, in this condition, is fit for this task.

Work through four questions:

1. Is there an open defect in the technical log? Read it before every flight. An entry that has not been signed off as rectified is an open question, not a historical note.
2. Is scheduled maintenance due or overdue? Check hours or cycles against the manufacturer's schedule. An aircraft due for a motor change at 200 hours is not serviceable at 205.
3. Does the physical inspection reveal anything? The walk-around covered in the multirotor chapter: airframe cracks, arm locks, motor free rotation, propeller condition, secure fasteners, connector condition, antenna integrity, battery condition.
4. Is the aircraft adequate for the specific task? A minor defect that is acceptable for a low-risk flight over an empty paddock may be unacceptable for a flight near people or infrastructure. A hexacopter with a marginal motor should not be flown over an asset where a second failure would be catastrophic.

That fourth question is the reason the wording is "for a specific operation". The same aircraft can be serviceable for one job and not for another on the same day.

Inspections

Schedule 4 topic 3(c)(i) makes conducting inspections of the RPA an explicit RePL holder responsibility. Three levels apply:

Pre-flight inspection, before every flight:

Post-flight inspection, after every flight: damage acquired in flight, propeller condition, motor and battery temperature, and anything the flight revealed. Then log it.

Scheduled maintenance, against the manufacturer's programme: hour- or cycle-based motor, bearing and propeller replacement, structural inspection, and battery retirement criteria.

Reporting Defects and Unserviceability

Schedule 4 topic 3(c)(ii) requires the RePL holder to report defects or unserviceability. That reporting runs in two directions.

Internally, to the operator:

• Enter every defect in the technical log at the time it is observed, with enough detail for someone else to act on it: what, when, in what phase of flight, with what symptoms.
• Notify the maintenance controller where the operator's DPP requires it, and always for anything that grounds the aircraft.
• Placard or physically segregate an unserviceable aircraft so the next pilot cannot inadvertently fly it. A note on a screen is easier to miss than a tag on the case.

Externally, where the occurrence is reportable:

• Reportable safety occurrences go to the ATSB under the Transport Safety Investigation Regulations (covered in the next section).
• Where a defect points to a design or manufacturing problem — a pattern of arm failures, a firmware behaviour that produces an uncommanded input — the manufacturer should be informed, and CASA may need to be where the safety implications are broad.

The judgement that matters most

The hardest airworthiness decision is not the obvious one. Nobody flies an aircraft with a cracked arm. The difficult call is the small, ambiguous item: a motor that has been slightly warm for a few flights, a propeller with a nick you could argue is cosmetic, a telemetry dropout that only happens at range, a battery whose cells take a little longer to balance than they used to.

Those are exactly the items that section 20AA(4) is aimed at, because "a defect that may endanger" is a low threshold deliberately. The professional answer is to write it in the technical log, ground the item if there is genuine doubt, and let the maintenance controller decide — rather than making a private judgement under time pressure with a client waiting. An aircraft that does not fly today costs a job. An aircraft that fails over a person costs considerably more.