Outside of commercial operations, aircraft are required to undergo a series of non-revenue test flights to verify particular aspects of airworthiness. The requirement to ensure airworthiness of an aircraft can be sought by different personnel or organizations.
A term used to describe such test flights are referred to as an “Acceptance Flight”, in which the aircraft performs a test flight prior to being signed off and approved by the relevant organization.
What is an Acceptance Flight?
An acceptance flight is a non-revenue, test flight performed by an aircraft prior to a transfer of operator or ownership. The primary reason behind acceptance flights is to verify that the aircraft meets the requirements and specifications stated on the relevant documentation.
An acceptance flight can identify the airworthiness state of the aircraft by the means of flight testing, in which various onboard systems are tested in-flight.
These tests should be conducted by appropriately qualified flight crew and engineers. The exact range of in-flight tests carried out will vary based on what type of transfer the aircraft is being processed through.
The extent of flight testing can range from a single test flight which can indicate the operational status of the aircraft to a series of test flights which intend to perform tests on a plethora of aircraft systems or to act as a follow-up test flight to the first acceptance flight.
A follow-up test flight may be scheduled in order to ensure issues identified on the initial acceptance flight have been resolved.
Pre-Delivery Acceptance Flights
When an aircraft has been rolled off the final assembly line of the production facility, the customer will arrive with its own flight crew and engineers to perform an acceptance flight prior to signing off and taking delivery of the aircraft.
On these pre-delivery flights, the airline’s personnel will be accompanied with test pilots and flight engineers from the manufacturer.
During the pre-delivery acceptance flight, the flight crew will fly the aircraft through a range of tests to ensure the systems are functioning correctly.
An on-ground element of the acceptance flight would also include the aircraft cabin being inspected by the customer to check that it matches the specifications stated.
During the pre-flight phase, the flight crew and engineers will conduct an extensive and thorough external inspection and walkaround of the aircraft.
Engineers will also perform additional inspections both internally and externally on the aircraft.
Pre-delivery acceptance flights are also referred to as customer acceptance flights.
Lease Transfer Acceptance Flights
At the end of a lease, an aircraft will undergo paperwork in regards to transfer of ownership/operator. This paperwork records and certifies the handover of the aircraft between 2 organizations (airlines or leasing companies).
Acceptance flights during lease transfers are particularly important in order to ensure the aircraft complies with airworthiness and maintenance records.
The maintenance and airworthiness management of the aircraft usually consist of a series of stipulations that form part of the lease agreement.
In order for the aircraft to be transferred or returned to the leasing company, the stipulations and conditions set out in the lease agreement must be complied with.
Failure to meet the requirements will mean that the lessee is required to perform necessary tasks in order to bring the aircraft up to an acceptable condition.
Acceptance Flight Requirements
The exact requirements for an acceptance flight varies based on the operator and the type of transfer occurring (lease transfer, pre-delivery).
However, there are a basic set of requirements found across all acceptance flights:
- Both organizations involved in the transfer must have a sufficient number of qualified personnel on-board – pilots, test pilots and engineers.
- Acceptance flights include extensive internal and external inspections of the aircraft – borescope inspection of the engines, aircraft cabin inspection etc.
- Acceptance flight must be of sufficient duration in order to ensure correct functioning of the aircraft’s systems and components.
- Aircraft and component paperwork and documentation must be up to date and match that of the actual status of the aircraft and its components.
Once these requirements are met along with any other stipulations stated in the legal agreement, the aircraft should successfully transfer between operators following the acceptance flight.