27th September 2005
SERVICE BULLETIN 270905
ATTACHMENT OF OIL HOSE TO ELBOW 924583
ON ROTAX OIL COOLERS AND OIL PUMP
Classification – Essential
Aircraft Affected – All microlight and homebuilt aircraft with Rotax 912UL, 912ULS and 914 UL engines if fitted with Rotax elbows, part No. 924583, on oil cooler and / or oil pump inlet. Excluded are Pegasus Quik and Quantum aircraft, which are covered by Pegasus Service Bulletin No. 118. The Bulletin does not apply if the oil cooler and oil pump inlet are fitted with barbed straight connectors (Rotax part No. 840449) or swivel straight connectors (956610) or swivel elbow connectors (956580).
Compliance – Inspect security of hoses fitted to Rotax elbow 924583 before further flight. Carry out additional security as detailed in this Bulletin within the next 10 operational hours.
Nature of Defect
A couple of cases have been reported of the oil hose separating from elbow 924583, which may be fitted to the Rotax oil cooler and/or the oil pump inlet. If the hose, and the clamp securing it to the elbow, are not positioned correctly, it is possible for the clamp to gradually squeeze the hose off. This may be more likely if the oil gets particularly hot, softening the reinforced rubber hose.
If a hose detaches with the engine running, the engine will be quickly starved of oil and may seize.
1) Before further flight check the security of hoses fitted onto elbows 924583. If there is
any doubt about the positioning of the hose and the clamp, the hose should be
removed, the elbow and hose degreased and cleaned, and refitted in the correct
position as detailed in 2) below. Take care not to contaminate the inside of the hose or
the elbow with rag when cleaning.
2) If the hose is removed, reposition as follows_
a) Mark the elbow 22mm from its end using an indelible marker (Fig.1).
b) Push the hose up to this mark and fit the clamp (Rotax part No. 853725) 7-8mm
from the hose end, with the fixing screw orientated as shown (Fig.2).
3) Fix a 12mm hose clamp (Skydrive part No. ‘Clamp 12’) to the end of the elbow with
the fixing screw orientated as shown in Fig.2. If the hose has not been removed the
clamp can be fitted by removing its screw and opening it until it fits over the elbow.
Tighten the clamp firmly.
Wire lock between the screws of the two clamps as shown, to give an additional
restraint to prevent the hose from coming off.
Photos 1 and 2 show the job completed on elbows fitted to an oil cooler and the oil
4) If any hose has been disconnected during this rectification, then the oil system must
be vented before the engine is started. This can be carried out by removing one
spark plug from each cylinder, and, with the ignition switched off, but the master
switch (powering the oil pressure gauge) on, turn the propeller in its normal
direction until an oil pressure reading of at least 1 bar is obtained.
Then turn off the master switch and replace the spark plugs, torquing to 20 Nm, and
replace the plug caps.
5) Carry out a short test run of the engine. After stopping it check for security of the hose
Record the completion of this Bulletin in the engine logbook and have entry signed off by
your BMAA or PFA inspector. Append a copy of this Service Bulletin to the aircraft
The security of the oil connections and the wire locking should of course be checked as
part of the daily inspection.