Slightly obscure this, but I hope one of the many here who have practical experience of restoring 1940s RAF types or are otherwise familiar with Type Records, DIS etc might have an answer.
The question is: What is the official difference between a Modification, an Alteration and an amendment?
For example: The Gladiator type record contains:
Mod No 13: Incorporation of stonger front body strut
Amendment No 14: Cancellation of GSP parts by AGS parts
Mod No 15: External bracing change from streamline wires to oval wires.
It seems as though Mods and Amendments are numbered in a single series and that Mods imply a change to the design of the aircraft or its equipment, while amendments are just corrections to drawings or changes to schedules of parts. Is this correct?
For the Whirlwind (Fighter not egg beater) we have:
Alteration No 8: Provision for TR 1133 as alternative to TR9
Alteration No 9: Fixed fittings for installtion of desert equipment
but we then have plenty of other changes described as “Modifications” – for example Mod 48 – deletion of mud guards.
Whether called Mods or alterations these are all changes in design rather than corrections to drawings, so what is the difference in meaning between the two? Or is it just a Westland habit with no official meaning at all?
Told you it was obscure.
NiallC
By: Papa Lima - 8th March 2006 at 16:53
From recalling my RAF days (working on radar, and an awfully long time ago), modifications were obligatory, whilst alterations were optional.
By: bloodnok - 8th March 2006 at 16:12
amendments are done to air publications, the one listed above is the change in terminology from general service parts to aircraft general spares (still in use today).
i’d say the difference between alteration and modification would be a mod is fleet wide, and covers all aircraft of that type, and is incorporated once the aircraft is in use. they are usually improvements in design that are incorporated once its in use.
alterations, i’d have thought are probably an up issue of a drawing used in manufacturing, such as adding the bracketry for desert equipment, this is kind of like a modification, but incorporated during the aircraft build.
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March 8, 2006 at 10:17 am