Rotax 912 and 914 Engines: Reciprocating Engine – Valve Push Rod Assembly – Inspection / Replacement
Applicability: Rotax 912 iS Sport, 912UL, 912ULS, 914UL engines. For Serial numbers affected refer to Rotax SB SB-912 i-008iS/SB-912-070UL / SB914-052UL at latest revision
Reason: Power loss and engine RPM drop have been reported on Rotax 912/914 engines in service. It has been determined that, due to a quality control deficiency in the manufacturing process of certain valve push-rod assemblies manufactured between 08 June 2016 and 02 October 2017 inclusive, partial wear on the rocker arm ball socket may occur, which may lead to malfunction of the valve train. This condition, if not detected and corrected, may lead to rough engine operation and loss of power, possibly resulting in a forced landing with consequent damage to the aeroplane and injury to occupants. To address this potential unsafe condition, BRP-Rotax issued Service Bulletin (SB) SB-912 i-008 / SB-912-070 / SB-914-052 (single document), providing applicable instructions. For the reason described above, this MPD requires a one-time inspection and, depending on findings, replacement of affected parts. This MPD also prohibits installation of affected parts on an engine. This MPD, for the uncertified engine variants, mirrors the EASA AD 2017-0208, which was for the certified engine variants.
Compliance/ Action: Required as indicated unless accomplished previously:
Note 1: Valve push-rod assemblies Part Number (P/N) 854861 are hereafter referred to as “valve push-rod”.
Note 2: BRP Rotax SB-912 i-008 / SB-912-070 / SB-914-052 (single document) is hereafter referred to as “the SB” (see link below).
Note 3: BRP Rotax SB-912 i-008iS / SB-912-070UL / SB-914-052UL (single document) is hereafter referred to as “the Applicability SB”
Note 4: Group 1 engines are those having a serial number (s/n) as listed in the Applicability SB (see Note 3); or an engine, having any s/n, on which a valve push-rod (see Note 1) has been replaced in service between 08 June 2016 and 18 February 2018 inclusive. Group 2 engines are those that are not Group 1.
Inspection: (1) For Group 1 engines (see Note 4): Within the compliance time identified in Table 1 below, as applicable, visually inspect the push-rod ball sockets of each valve push-rod in accordance with the instructions of the SB.
Table 1 – Visual Inspection of Affected Assembly
|Engine Flight Hours (FH) since first installation on an aircraft||Compliance Time
|160 FH or less
|Before exceeding 170 FH since first installation of the engine on an aircraft, or within 3 months after 18 February 2018, whichever occurs first.|
|More than 160 FH
|Within 10 FH or 3 months, whichever occurs first after 18 February 2018.|
Corrective action: (2) If, during the inspection as required by paragraph (1), a valve push-rod having black surface is detected (reference Fig. 1 in the SB), before next flight, replace that valve push-rod and its affected parts (see Note 5) with serviceable ones in accordance with the instructions of the SB.
Note 5: Affected parts are listed in Table 2.
Table 2 – Affected Part
|Vale push-rod assembly
|Rocker arm left
|Rocker arm right
Part installation: (3) For Group 1 and Group 2 engines: From the 18 February 2018, it is prohibited to install on any engine a valve push-rod (see Note 1) manufactured between 08 June 2016 and 02 October 2017 inclusive.
ENSURE COMPLIANCE WITH THIS MPD/SB IS RECORDED IN THE AIRCRAFT LOGBOOK
Further information is available at the following links:
EASA Airworthiness Directive (Certified Aircraft Only, included for Reference)