Fiat/Ansaldo A.C.4 — Engine & Assembly Manuals Collection

Primary-source technical documentation for the Fiat/Ansaldo A.C.4, the single-seat fighter prototype developed by Aeronautica d'Italia S.A. (Torino) in the mid-1920s. Only one prototype was ever built and flown, in 1927, making surviving factory documentation of exceptional rarity. This collection brings together the two known surviving primary-source manuals for the airframe and its powerplant.

Documents in This Collection — 2 Manuals

1. Fiat A.20 Series IV Aircraft Engine — Operating Instructions, 1929

Istruzioni per l'Uso del Motore Fiat A-20, IV Serie
Ministero dell'Aeronautica — Direzione Generale delle Costruzioni e degli Approvvigionamenti
Published: Roma, Provveditorato Generale dello Stato — Libreria, 1929 (Anno VII)
Language: Italian

Official operating instructions for the Fiat A.20 V12 inline water-cooled engine (410 hp) as fitted to the A.C.4 prototype. Covers engine operation, maintenance intervals, and valve-timing procedures. The Fiat A.20 was shared with the Fiat CR.20 fighter programme, making this document a cross-reference source for both aircraft families.

2. Aircraft Assembly and Adjustment Instructions — 1928

Apparecchio A.C.4 — Istruzioni per il Montaggio e la Regolazione
Aeronautica d'Italia S.A., Torino — Ministero dell'Aeronautica, Direzione Generale del Genio Aeronautico
Published: Roma, Provveditorato Generale dello Stato — Libreria, 1928
Language: Italian

Factory assembly and adjustment manual for the A.C.4 airframe. Covers physical layout schematics, wing rigging specifications, and adjustment procedures as used during the prototype's 1927–1928 assembly and evaluation phase. The A.C.4 was a parasol-wing monoplane derived from licensed Dewoitine D.1 design principles, armed with twin 7.7 mm Vickers machine guns synchronized through the propeller arc.

Historical Context

The A.C.4 programme was retired on 15 February 1929 after evaluation by the Regia Aeronautica, which favoured the superior biplane fighter designs then available — principally the Fiat CR.20. The single prototype was struck from the service registry in 1929. These two documents represent the primary surviving technical record of the aircraft.

Configuration: Parasol-wing monoplane (derived from licensed Dewoitine D.1 designs)
Engine: Fiat A.20 V12 inline water-cooled — 410 hp
Armament: Twin 7.7 mm Vickers machine guns, synchronized
Programme closed: 15 February 1929

This is an archival, static-copy edition fixed at its original publication date. Intended for historical reference, flight simulation, museum restoration, and educational use only. Not approved for active airworthiness maintenance under FAA 14 CFR § 43.13, EASA Part-M, or equivalent international regulations. Operators of active aircraft must use current, revision-controlled publications from the Type Certificate holder or an authorized distributor.

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