Rotax 914 / airframe question

[gyroplanes]

This scares me a bit, after starting my Sycamore (914 Rotax) effortlessly, and restarting it with someone else at the controls, it quit starting the gyro after 3 tries.
I jumped it with my NOCO jump pack (great unit) and taxied it around. it was dusk and I had all my lights on.. The lights all went out and surprised me a bit. As I headed back to the hangar the engine started misfiring and died.

I believed that once running, the alternator would easily carry the engine and lights load. I also believed that the magneto(s) would keep the engine alive. I had an ah ha moment when I remembered that I have 2 electrical fuel pumps, one as a reserve. But if neither pumps run the magnetos won't run an engine that isn't getting fuel. I need an Auxiliary battery and system to switch to it. Bummer, I thought it was ready to fly?

What do you 914 operators do for redundancy?

 

[Abid]

Charge your battery completely. At idle you are not going to get a lot of amps. Start with one pump only. Taxi with one pump. Turn 2nd pump only for takeoff and pattern work in the runup area. Don't turn all lights on. Just taxi lights and hopefully they are LED. You don't need aux battery. You need to really understand how Rotax electric system works and not start out with a battery that already needs a jump start. Your battery should be a 14 or better 17 AH capacity battery in a 914. At idle you get maybe 8 to 9 amps. Idle is 1800 RPM. Above 3000 you will be getting in excess of 18 amps.

 

[gyroplanes]

Charge your battery completely. At idle you are not going to get a lot of amps. Start with one pump only. Taxi with one pump. Turn 2nd pump only for takeoff and pattern work in the runup area. Don't turn all lights on. Just taxi lights and hopefully they are LED. You don't need aux battery. You need to really understand how Rotax electric system works and not start out with a battery that already needs a jump start. Your battery should be a 14 or better 17 AH capacity battery in a 914. At idle you get maybe 8 to 9 amps. Idle is 1800 RPM. Above 3000 you will be getting in excess of 18 amps.

Thank you for the reply. I really want to know what you 914 operators are doing for redundancy on the electrical fuel pump issue. If you lose electrical, you will lose both pumps?

 

[Sv.grainne]

See my post similar thread. Replace the Ducati rectifier/regulator with a B&C. I was amazed at the improved power capacity even at idle.

 

[GyrOZprey]

I had an Edge Performance 15 amp auxiliary alternator installed - to boost my electrical needs on my EP fuel-injected modified 914!

TAGNA partner Tim Weiland is delighted with the EP 15 amp & 22 amp add-on alternators for extra electrical security on dual fuel-pump, & fuel injection engines!

 

[Abid]

Thank you for the reply. I really want to know what you 914 operators are doing for redundancy on the electrical fuel pump issue. If you lose electrical, you will lose both pumps?

I do nothing. Rotax advises nothing besides the right capacity battery. You lose your charging circuit, you will have the charging lamp come on and/or you will see your voltage go down. usually with charging circuit working and properly connected you will see 13.5 to 14 volts. If charging circuit fails at the rectifier the lamp will come on. If charging connection fails past that you will notice your voltage that used to read 13.6 to 14 now reads 13 or 12.9 volts. Now you are running on your battery alone and it will start discharging slowly. That is your backup. In this case, you should turn off all non-essential electrical consumers (like lights,2nd fuel pump, other avionics that aren't crucial to flight) and continue to closest safe airport or spot to land. You should have about 1 hour with a 14 AH to land before your single fuel pump will quit.
In your case, your battery started out discharged and you decided to run the whole shebang on it and that too on idle. No wonder, discharged battery with idle RPM and all consumers turned on, your backup which would be a normally charged battery was already gone. Also means your charging circuit isn't really charging and is connected incorrectly. You need to learn the charging circuit and fix that as one. And start with a properly charged 14 to 17 AH battery as your 1 to 2 hour backup.

 

[Abid]

I had an Edge Performance 15 amp auxiliary alternator installed - to boost my electrical needs on my EP fuel-injected modified 914!

TAGNA partner Tim Weiland is delighted with the EP 15 amp & 22 amp add-on alternators for extra electrical security on dual fuel-pump, & fuel injection engines!

EP fel pumps are Bsch and they consume a huge 9 amps per pump. However that is unnecessary for 914 whose fuel pumps only need 5 psi pressure.

 

[martin-av8r]

upper choice for 914

lower link all the choice , flow , pressure , amp , EP select for each engine design need , NA , turbo , BSFC , flow , pressure

Walbro GSL Series Inline Fuel Pumps (Universal)

Walbro GSL series inline fuel pumps are ideal fuel pump replacements and upgrades for: - Vehicles with faulty inline (external) fuel pumps. - Vehicles with expensive or hard to replace intank fuel pumps. - Vehicles used for racing or performance purposes where higher pressure fuel is necessary.

walbrofuelpumps.com