AD för Rotaxmotorer

AD berör kontroll av cylindertopp, ATA 72 – Engine – Engine Cylinder Head – Inspection / Replacement.

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Reason:
A design change of the engine cylinder heads was introduced by BRP-Powertrain in March 2013 which modifies the engine/aircraft interfaces by substituting the previous cylinder head temperature (CHT) measurement (limit temperature 135°C/150°C) with a coolant temperature (CT) measurement (limit temperature 120°C).
The design change was communicated on 15 May 2013 by BRP-Powertrain Service Instruction (SI) 912-020R7/914-022R7 (single document) but was not identified by a change of the engine modeldesignation or of the engine P/N, but only through the cylinder head P/N and the position of the temperature sensor.
Consequently, engines with the new cylinder heads (installed during production or replaced in-service during maintenance) may be installed on an aircraft without concurrent modification of that aircraft, instructions for which should be provided by the Type Certificate (TC) holder or Supplemental Type Certificate (STC) holder, as applicable. In this case, the coolant temperature with a maximum engine operating limit of 120°C (valid for engines operated with water diluted glycol coolant) is displayed on a CHT indicator with a typical limit marking (red radial/range) of more than 120°C.
This condition, if not detected and corrected, will prevent the pilot to identify coolant limit exceedances, with subsequent loss of coolant (120°C is the boiling temperature of the coolant), which could lead to engine in-flight shut-down, possibly resulting in a forced landing, with consequent damage to the aircraft and injury to occupants.

For the reason stated above, this AD requires a one-time inspection to determine the actual engine configuration and, depending on findings, engine reidentification and (depending on TC or STC holder installation) modification of the affected aircraft. This also affects engines that are operated with waterless coolant.