A non-homologated clutch mechanism and an apparently oversized turbo-compressor turbine wheel are the issues that led to Mikko Hirvonen's exclusion from Rally of Portugal victory, according to the stewards' documents that have now been released by the organizers.
The decision is based on a report carried out by FIA technical delegate Jerome Toquet, which found the clutch mechanism did not comply with homologation form A5733 and the turbocompressor turbine wheel apparently over the maximum dimension.
Citroen team principal Yves Matton, team manager Daniel Grataloup and technical director Xavier Mestelan-Pinon were all questioned by the stewards at 8.30pm local time on Sunday.
The stewards' decision, delivered at 10:45 p.m., stated: "On being questioned, Mestelan-Pinon explained that the clutch was a 'joker' part introduced as provided for in the regulations and agreed that the part removed from the car during post-event scrutineering did not match that shown on the homologation form. He also explained that the clutch removed from the car was from a different batch number to that shown on the homologation form. He stated that this was clearly a big mistake and was unsure how it happened.
"In the case of the turbo, the Citroen representative stated that the turbo unit was a standard unit provided by the specialist manufacturer Garrett who, in fact, provided the turbo units for all World Rally Cars.
"He explained that the turbine wheel was subject to extreme temperature and rpm factors which had an effect on the wheel dimensions. He added that this aspect had been the subject of discussions with the FIA technical department.
"It is noted that the homologation papers state that the dimension C is given as 54.00mm with a tolerance of plus/minus 0.1mm. Mestelan-Pinon stated that the new turbine wheel when measured, was 54.02mm, which is very close to the specified dimension, including the tolerance The wheel will be measured again under laboratory conditions."
The officials decided the clutch issue was sufficient to require a disqualification, with the turbo irregularity still an open matter.
"The clutch fitted is not in conformity and therefore car number two is excluded from the event classification," said the stewards' report. "The turbo appears not to be in conformity, however, the stewards suspend a decision on this matter and request the FIA technical delegate carries out further investigation."
Hirvonen's exclusion means Mads Ostberg has secured his first World Rally Championship win.