Turbine engine ignitors

ljg

ljg

Well-Known Member
Is there any reason we don't leave igniters on all the time for an added margin of safety, other than the increased wear and tear?

Thanks guys.
 
Unless you run out of fuel that fire is not going out (outside of maybe heavy rain with turbulence and a major malfunction) so theres no need for constant ignition. Its just that simple.
 
You've got the fire going....if the fire stops, you of course have a procedure for lighting it back up, which includes firing the ignitors again. In terms of wear and tear on the ignitors themselves, it just wouldn't really make sense to use them all the time to prevent that one occurence in thousands where you have a flameout which could actually have been prevented by continuous use of ignitors. Just my .02
 
BajtheJino said:
Unless you run out of fuel that fire is not going out (outside of maybe heavy rain with turbulence and a major malfunction) so theres no need for constant ignition. Its just that simple.
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No maybe about those particular situations you mention; they have and do happen. And a good number of planes have continuous ignition as the norm.
 
MikeD said:
No maybe about those particular situations you mention; they have and do happen. And a good number of planes have continuous ignition as the norm.
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On that note... maybe a moo driver can explain this "auto ignitors" I keep hearing tell of. The only "auto" I've ever been aware of for the ignitors is when you hit the start button/switch...

-mini
 
Our plane (ERJ) with Rolls Royce engines/Fadec have an "Auto" position...If the FADEC senses an impending flameout it turns on it's corresponding ignitor. It's fairly rare to see in flight and just pops up for a second, on the ground I see it occasionally during taxi when I bring the power back to idle. Of course we can select them "ON" as well when conditions warrant.
 
Per the "autoignition", it was a function in my old airplane (powered by a PT6). Basically it was a standby system that switched on when it was energized (autoignition switch "on") and the engine torque dropped down into the 200 ft-lb range or so. It was a safeguard used whenever penetrating thunderstorms or extremely foul weather/hail/etc, or when doing aerobatics.
 
minitour said:
On that note... maybe a moo driver can explain this "auto ignitors" I keep hearing tell of. The only "auto" I've ever been aware of for the ignitors is when you hit the start button/switch...

-mini
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The T-38, for example, puts the ignitors on every time you move the throttles from MIL into afterburner.

The F-100-PW-229 engine in the F-15E runs via an I-DEEC, which has ignition sensors and will automatically fire up the ignitors when it senses the potential for compressor stall or any other number of potential engine problems.
 
There are auto ignitors in the Hawker, thanks to the left hand of the guy in the right seat.

For example: "Hey Bill, how bout hittin them ignitors for me?"
 
Our PC-12 has auto ignitors. The switch has the auto and on positions. Like mentioned above we only switch to "on" position in heavy precipitation or turbulence.
 
In the CRJ, the continuous ignition comes on automatically if the AOA vanes sense an impending stall. Our Limitations recommend manual arming of continuous ignition for the following scenarios:

- Contaminated Runway
- Mod/Heavy Turbulence
- Mod/Heavy Precipitation
- In the vicinity of thunderstorms
- Strong Crosswinds (excess of 15 knots steady state)


Windshear isn't listed, but I would consider that a strong wind condition.
 
The CF6s run a continuous ignition, which comes on when:

AntiIce is on - auto feature

You turn it on for (pretty much what'll snuff the flame):
Heavy Rain
Ice - automatic as above
Volcanic Ash
Standing water or slush on the runway
Severe turbulence


I ran auto ignitors for about 9 years on embraer products and never saw them kick on in flight.
 
Polar742 said:
The CF6s run a continuous ignition, which comes on when:

AntiIce is on - auto feature

You turn it on for (pretty much what'll snuff the flame):
Heavy Rain
Ice - automatic as above
Volcanic Ash
Standing water or slush on the runway
Severe turbulence


I ran auto ignitors for about 9 years on embraer products and never saw them kick on in flight.
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I saw it once. It was on OE of all of the trips.

We were cruising along, fat dumb and happy while talking to some center controller. We were on the phone with the FA, probably attempting to stay awake (16 hour day, lots of delays). All of a sudden me and the captain say in unison "What the was that!" as the airplane starts to yaw. We get our eyes to the EICAS just in time to see N1 on number 1 spooling back up through about 70%, ignitors on and the FADEC swapped over to the B computer.

We, in fact, had a full engine shutdown and relight out at FL370 without us touching a thing. Our best guess, and the mechanics best guess was that FADEC A crapped the bed and as such, the FPMU closed and the engine proceeded to shutdown. As that happened, B saw that the engine was shutting down and took over, doing an auto relight, obviously engaging the ignitors.

Who knew the system would actually work as advertised. I always thought it was a little bit too much black magic for me, but it worked without question for us!
 
I've only seen it in the sim but on the 700 the FADEC will attempt an autorelight if an engine flames out and it doesn't think there is any structural damage. It's a nice feature but is annoying as hell because as the engine spools down you throw in rudder to correct and then it relights and you are way overcorrected and skidding all over the place.
 
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