Maintenance of Aircraft under “B” conditions: 

The maintenance of aircraft flying under "B" conditions must be adequate in relation to the number and duration of the flights. If a prolonged sequence of flights is expected, a programme of maintenance must be prepared. Procedures shall be in place to ensure that provision is made for any additional maintenance which may arise from development or modification of the aircraft whilst under "B" conditions.

The aircraft shall be certified as 'fit for flight' after maintenance in accordance with the preceding paragraph.

On completion of all flights under "B" conditions, a Flight Test Certificate must be completed by the pilot/captain and all annotated defects rectified or re-tested.

Once the first flight has been satisfactory completed, a series of subsequent flights establish the airworthiness of the aircraft with regards to speed and height envelopes, noise, specific fuel consumption, handling qualities and many other characteristics needing to be quantified.

Each flight must be in accordance with a flight test schedule which has been drawn up by the manufacturer and approved by the C.A.A. (See extract from BCAR A2-3 below)

The applicant shall submit for approval a flight test schedule, containing details of the proposed flight tests to be included in the Airworthiness Acceptance Trials. This schedule shall include the flight tests necessary: 

(a) To establish compliance with the appropriate airworthiness requirements.

(b) To provide information for inclusion in the documents associated with the Certificate of Airworthiness (Or Permit to Fly - see later).

NOTE:    The C.A.A. may require alterations to the flight test schedule, and may also require additional tests not included in the schedule if it appears that such test are necessary to establish the airworthiness of the aircraft type.