The introduction of retracting undercarriages in the Thirties added another task for the AID, in testing their actuation. Seen here is the port undercarriage unit of a Bristol Blenheim.

Camouflage and markings were also a matter for AID checking: not just the disruptive pattern, but the detailed stencilled markings, in black or white to contrast with the background, giving assembly numbers and doping scheme - Cellon X in the case of fifth production Bristol Blenheim I K7037, seen in this view.

The cockpit of a Vickers Vimy. Control cables were checked for strength as well as for correct operation, and were tagged as evidence of inspection.

"Vickers-Vimys" for China: A batch of Vickers-Vimy-Commercial machines in various stages of erecting at the Weybridge works of Messrs. Vickers, Ltd.
Vickers Vernon Is ready for pre-covering inspection of their fuselages at Weybridge. The AID was responsible for inspecting both military and civil aircraft from 1919 to 1937.

Interior view of a Vernon showing stretcher (top) and troop seats. AID checks ensured that all airframe attachments were secured against vibration.