Rotax 503

[Pieter85]

Dear all please assist,

During our flight on last sunday, we encountered power loss due to fuel starvation. Engine approx 19 hours in total on the Rotax 503. additional e-fuel pump have been installed and is perfectly in working order.

Regards
Pieter

[nickjaxe]

Do you have one of those rubber hand primer pumps fitted???? and was the e pump fitted after the power loss.

[Dobbs]

What makes you sure that it was fuel starvation?

Have you ruled out carb icing?

If you are sure that it is fuel starvation, was it on take off with a nose high attitude, staright and level etc. Some fuel lines, when old, tend to swell and reduce the ID resulting in possible reduced fuel flow

If you are certain that it was fuel starvation, and your fuel filter is clean, checking the float level set up would be a good place to start.

Hope you come right soon.

[nicow]

It can be the fuel pump What is the pressure that the pump pumps,was it on,and what size pipes do you use?
How much fuel was in the fuel tank?
Maybe it was Carb ice....

[johnythelaw]

HI EVERYONE
I have been with Pieter in the plane and made a safe precautionary landing without any scratches to man or machine.
1) The electric fuel pump is a normal square no name pump from Car dealers and looking at the logbooks afterwards
the pump was fitted after the inital test flights was done and there they also mentioned a fuel starvation.
2) the electric pump was on from takeoff to landing with approx 15 minutes of flying.
3) the see through plastic fuel lines to the carbs from the normal pump was full of air with some fuel still left in the lines.
4) The engine was running smooth at idling approx 2300 rpm and as soon as i opened the throttle rpm went up to 2700 rpm
but then acted like a carburetor that was choked by hand with too litlle air.( and no power )
5) fuel line clamps was cheap stuff and when bent by hand the electric pump forced fuel past the clamp.
Re starting the engine was no problem with some fuel in the floats and 25 liters in the tank.
By the way flight was at sea level with temperatures of guessing 18 degrees and 1000 feet ( carb ice ? i dont know)

We replaced the clamps with good quality clamps as it could suck air past the clamps , if it could force fuel out past the clamps.
The filter looks clean and is one of the Mercedes type that most guys reccommend. This will be replaced before next flight.

Now the big question to all with experience
Do we start the motor with electric pump on or off?
Do we only put the electric pump on with takeoff and switch off with level fligt as most normal pipers and cessnas
( electric pump was runing but reduced power when it happened)
Is the standard pump strong enougth to suck petrol from the tank to the carbs which is approx 1 m higher than the tank on the challenger.
All trikes etc the tank is way below the engines.
Should i perhaps replace the standard pump with a new one although it only did 19 hours sinse new ( ne stuff could also be faulty)
Any info or comment will be appreciated
Next fligts will be very near and overhead the field until very sure all is fine

For statistics : This was my first off field landing in 39 years of flying and 2500 hours ( had some trouble but always made it home to airstrip)
Pieter is due to start his training shortly { shows what the chances are, so do good training and always fly according to the rules)

Regards
Pieter and Johan

[nickjaxe]

Its not over-pressurising the fuel sys is it???

[martinhiggs]

Dear all please assist,

we encountered power loss due to fuel starvation.

Regards
Pieter

This usually results from improper preflight planning or improper fuel management procedures.

[mulderpm]

Difficult to say but the transparrent pipes when exposed to fuel become hard and they pull away from the clamps. I have had fuel being pushed past the pipe after the fuel pump and air sucked in before the pump. I check for this during every pre-flight and once or twice a month check all the clamps for tightness. I have had the same problems with my previous rubber fuel lines so that is not the answer either. The clamp sinks into the rubber and the rubber cracks.

The safest is to replace these cheap pipes at or before every ATF and only use good quality clamps like, Oetiker. See http://www.clamps.co.za.

[Duck Rogers]

Dear all please assist,

we encountered power loss due to fuel starvation.

Regards
Pieter

This usually results from improper preflight planning or improper fuel management procedures.

Rubbish!

[bobthebuilder]

As a matter of interest, what airframe is attached to the engine?
I am a little confused about the pump. How long has it been in service? (Tried and tested?)
Was any work carried out recently?
Are you getting full power on a ground run?
Do you have EGT's?

Duck .... if this was a fuel starvation problem, would the EGT's not register a higher temperature as the engine runs lean?

[johnythelaw]

Hi everyone
The engine is in a challenger 11.
This weekend we found the problem.
Although the engine has only done approx 20 hours the plane has been standing for about 2 years.
The plastic see through pipes is hard and at every clamp - from fuel filter to electric pump and the mechanical pump
is sucking air if you bend the pipe a little near the clamp.
So the answer is replace the whole lot from the tank to the carburators with new piping and use proper clamps
This operation is not that expensive and then we will test it again.

This weekend we roped the aircraft and pushed the revs up to 5000 plus and as soon as it starts drawing a lot of fuel
litlle bubbles start entering the system at the clamps especialy the fuel filter clamp

I am quite possitive we will get it right and fly next weekend

Many thanks for everyones suggestions etc- this is what put you on the right track


regards
Pieter and Johan

[Duck Rogers]

Duck .... if this was a fuel starvation problem, would the EGT's not register a higher temperature as the engine runs lean?

Indeed it would...........
Dunno if this engine's got them fitted though