Technical response from Paul Magès to Maître Falque — Delmont Case (28 October 1970)

In this document

A technical defense note for litigation

This four-page document is the response from Paul Magès, Chief Engineer at the B.E.A., to Maître Falque of Citroën's legal department, in the context of the "Delmont Case" pp. 128-131. Page 128 is an initial summary note dated and signed "28.10.70"; pages 129-131 constitute a more detailed and numbered argument (points 1° to 17°).

The central technical argument

Magès explains that an incident can be "possible" or "impossible" depending on the technique used. He takes the example of the gear selector: in "neutral", it connects the clutch cylinder to the pressure source, which "necessarily causes the engine to disengage" p. 128. He concludes that it is technically impossible for Maître Delmont's car to have been driven for 10 meters with the lever in neutral p. 128.

The evidence invoked

Magès relies on several elements:

• the gendarmerie report, which found the lever in the first gear position p. 129;
• the report by expert Fresel, commissioned by the Evreux High Court, which deems this hypothesis "the only one to be retained" p. 129;
• Maître Delmont's failure to follow the instructions in the manual, which recommend pressing the brake p. 129;
• a previous incident reported by Delmont himself during his interrogation by Commissioner Lorin p. 130;
• the reports by engineer Doré on the technical reasons p. 131.

Examination of the opposing "four letters"

Maître Delmont cited four testimonies of incidents on DS to prove a construction defect. Magès comments on them one by one p. 131: the Montarnal case is a breakdown without a possible accident; the Davau and Harrewyn cases are explained by a start without hydraulic pressure and a poorly tightened parking brake; the Bohbot case, mentioning a reverse gear engaging on its own in neutral, is deemed "not serious" and implausible. Finally, Magès proposes demonstrations in the presence of experts and the judiciary p. 131.

Context

The "Delmont Case" is part of the context of the DS and their Citroën hydraulic system, designed by Magès, which controls the suspension, steering, brakes, and clutch simultaneously. This type of litigation, where the manufacturer had to demonstrate the technical impossibility of an "untimely start", was common at the time for vehicles with hydraulic assistance, which were then little known to the general public and sometimes misused (absence of a tightened parking brake, ignorance of instructions).

Archivist's perspective

This document is valuable because it shows Magès not only as an engineer but as a direct defender of his own invention before the courts, assuming a responsibility he himself describes as "moral" p. 129. The tone is convincing and pedagogical, almost didactic, revealing his mastery of the system he designed.

It seems that this piece is part of a broader effort to monitor the hydraulic reliability of the DS, in continuity with other internal notes by Magès on the operational safety of the hydraulics or on incidents reported from the field, which testify to constant vigilance in the face of malfunctions reported by users.