Engineering Day – Skycraft Jabiru Course 1

What a fantastic day with a great bunch of people ….

Flew out from misty foggy Jersey yesterday to even mistier and foggier Gatwick and then long drive up to Holbeach to stay in a small pup overnight ahead of today’s starter course for those who want to know a bit more about the Jabiru 2200 engine.

Started with lubrication … a very good place to start …

Next … electrics … not everyone’s favourite …

Next … mechanical bits … valves and tappers and compressions ….

Other useful bits to write up from my little notebook.

  • Oil breather pipe should rise initially before dropping away to catch bottle …
  • Oil excess overflow should not have a drain pipe that could end up pressurising the crankcase
  • Carb balance air pipe should come from filtered side of carb and into filtered side of air filter …should intrude by 20mm for good fit
  • Check the carb is earthed to engine
  • Flywheel bolts now have special new nordloc washers and new bolts ..old bolts need changing at 100 hours .. new ones won’t … the old ones could well be difficult to get out…remove spider … heat can be used to break the loctite .. but .. make sure you protect the magnets .. once heated .. let it cool right down first before trying to break the seal
  • When setting tappets ALWAYS do it cold .. so good plan .. drain oil hot from a run .. leave overnight to fully drain … then take a plug out to reduce turn pressure on prop and get piston to TDC then adjust as above
  • Good idea to make a mark on stator for where TDC is per cylinder
  • Check the small bung grub screws inside the tapper cover head .. these can come loose and cause oil to spill down thetappet pushrod guide tubes .. think I may well have this on mine !
  • Push rod tubes are rubber o ringed at bottom and circlipped at top
  • When replacing the inlet manifold rubbers .. prob best to cut the old ones off .. remove jubilee clips … then a bit of grease and turn the outer manifold pipe through 45’ .. it’s only on a rubber o ring to turning it makes new pipe slip on really easy
  • Note .. when checking torque on ALL cylinder head bolts .. start at 23 ft lbs and remove the bung acts which allows long drive access to 5th head bolt for torquing
  • All electrical parts should be Bosch .. distributor cap, rotor arms etc
  • Remember the ‘hidden’ filter in the pump
  • Oil pump return valve spring and fitting … push check … to make sure it’s free moving
  • Jabiru carb needle jet options … AUS vs U.K. … N2 for U.K. with fully tapered jet needle vs single bar straight sided needle for AUS market and weather conditions

Approvals ….

Got an email from the busy LAA this morning … working on a Saturday … so good to get feedback.

Having never submitted an aircraft modification before I am still learning the sequence and paperwork that is required.

The 12 pages of what is called a MOD3 went through quite a lot of iterations but, even though we have now reached a high degree of acceptance I have omitted to provide some other elements:

  • A completed worksheet – basically setting out the key elements
  • An updated section for inserting in the Pilot Operating Handbook POH
  • A PMR – Permit Maintenance Release

Spent this evening completing these so just need to meet up with my local LAA engineer for counter signature ..

Update to POH

POH Addendum Smoke System
Smoke System – Principle of Operation
The oil smoke tank uses a kit supplied by American supplier Smokin Airplanes and comprises the following elements:
– Smoke oil tank with associated pump
– Feed pipes and delivery pipes
– Spray bar fittings for exhaust pipes
– Electrical switches and fuses

The tank accepts a paraffin based oil (Baby oil) and the electrical switch , momentary switch provides power to the pump which draws oil from the tank into aircraft grade aeroquip rubber hosing.
The hosing routes to the rear of the stainless bulkhead and passes into a T bar aeroquip fitting that splits the single feed into a steel braided double feed that connects to spray bar atomiser injectors fitted into each exhaust outlet.

Fitting Of Oil Tank
The oil tank is fitted into the front seat (P2) location. The seat base and seat back are removed prior to installing. This leaves the Sherwood standard plywood seat base which has had 2 holes drilled in to accept 2 alloy pins on the underside of a tailor made ally mounting tray.
The mounting tray has lips on all sides to ensure the oil tank does not move in any direction.
Underneath the plywood seat base 2 alloy brackets have been riveted in position on the outer edge of the 2 longitudinal seat rails. These brackets accept a 1” wide ratchet strap.

Weight and Balance Consideration
As the oil tank is located in the P2 position, and this location is dead centre on the C of G , mainspar there is no change to weight and balance whether the oil tank is empty or full.

Filling the Tank
The tank is generally filled outside the aircraft but it can be filled in situ with a suitable long stemmed filler flex pipe. Filling is through a large hole in the top of the tank which has a securing screw cap. Do not overfill the tank .. 3/4 is sufficient for approx 4 mins of continuous smoke.

There is an overflow pipe if excess washes over in any steep turns. This pipe routes to the underside of the aircraft behind the u/c.
A quick release break valve is fitted to prevent spillage. The tank can be removed , even if oil remains in the tank.

Smoke Operation
The smoke can be operated once the engine reaches suitable temperature. Usually 150’ and above EGT.

There are 3 ways of operating the smoke:
– The main switch panel has a 3 position switch, continuous on, Off and Armed for intermittent
– A remote Push button allows momentary operation of smoke .. IF the primary switch is in the UP (Momentry) position
– If the primary switch is set to ON, the. The pump operates until it is turned off.

Note .. a red light is illuminated all the time the pump is in operation
Note .. the pump will continue to operate even if no oil is in the tank amd the switch is in the ON position.

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