Engine stopped

[kens_cockpit]

Only just worked up the courage to post this. Constructive comments welcome, particularly those directed at solutions. Keep the flamethrowers stored.

About 1 month ago during Phase 1 testing.

Top of the first ever stall turn.

Left rudder. Yaw established. Throttle to idle. Propellor stops.

Fail to restart in air.

Land in paddock.

Check over of plane and paddock. Engine restarts and runs normally including normal runups.

Short field take off and climb to safe altitude over the paddock and fly 10 minutes back to base airfield.

Put the aircraft away for another day.

This has put a real cloud over what is otherwise a lovely plane. I feel I can never have confidence in it or myself again.

Why did the engine stop?

Configuration

RV8

YO320 D1A

New from Vans in 2015 run for 162 hours on another RV8 then removed and installed on mine. All ground testing and in flight testing appeared normal until this incident except low oil temp which I’m still trying to fix.

Avstar Carb LVC-5-4PA

Idle was a bit low and mixture a bit lean initially but adjusted them long before this flight.

Standard Vans FAB

Slick mags

Engine driven fuel pump that came with the engine

Facet electric fuel pump ES 40108

Aircraft Spruce gascolator

Whirlwind GA200L propellor.

Flop tube on right tank. Standard pickup on left tank. Tanks about half full at time of engine failure.

I had been gradually expanding the envelope in Phase 1 testing including steep turns to 3.6g (the plane could take more but I can’t at the moment) and pushovers to -0.6g which led to the engine producing no power until positive g is reintroduced. That is what I think I should expect of the carbureted engine.

Multiple stalls in all configurations, loops and barrel rolls were completed with no indication of this sort of issue.

Before next flight after the engine failure I checked the fuel flow to the carby and the filter screen in gascolator. Both apparently normal.

Next flight did some stalls and circuits. Again all benign.

The plane and engine appear to operate normally in the ordinary flight envelope of take off climb cruise and descent.

The second flight after the engine failure at the end of climb and glide performance testing I did some higher angle climbs between about 5000 and 6000 feet amsl. At that point the tanks had approx 65 liters each side.

Starting at 130 kts I did a number of climbs working up to 30 degrees to 40 degrees nose above the horizon with throttle fully open and mixture rich and the electric boost pump on. At the top of the climb as the speed deteriorates to close to stall speed the engine starts to lose power although the throttle is still fully open. At that point the fuel pressure is still approx 4.8-5psi. Allowing the nose to drop restores normal power. That is the case for both fuel tanks.

I don’t know what the fuel flow is at that point. I have downloaded the Dynon data but the spreadsheet is so enormous I don’t know how to make it useful to find what is happening. I suspect the fuel flow is dropping dramatically there.

On the occasion of the engine failure I think I pulled the throttle to idle too soon. Poor technique. Neil Williams in the Bible on aerobatics advises keeping the throttle fully open until the vertical down line is established for a left stall turn. I have spoken to another experienced RV instructor who advises the same. But the subsequent climb testing shows that would not have made any difference.

What is going on here?

I don’t think the tank unported in the stall turn because the problem can be reproduced with almost full tanks without yaw or bank and the fuel pressure remains at the upper end even when the engine stops producing power.

Is this normal for a carbureted engine?

Perhaps the top of the climb is the top of a parabola producing less than 1g or approaching 0g resulting in the carb not distributing the fuel.

Do I have to avoid low-speed, low-g, high nose-angle manouvres like stall turns without fuel injection particularly with the low inertia carbon fiber propellor?

Should I get the carb checked? What should they be looking for when it is checked?

There is an explanation for the failure to get the engine restarted in the air. Multiple factors including high stress and not bringing to mind the need to turn off the non impulse coupled mag so that the starter would engage. Whether that was a good design decision is an issue for another day. I’ve changed my emergency checks to accommodate that design. Indeed if I had properly done my existing checks the engine likely would have restarted.

Whether I should have flown out of the paddock or left it for the insurance company is also a question for another day.

What I am interested in is why the engine stopped and what I need to do to prevent it happening again.

Wisdom on that issue please.

 

[lr172]

Well, pulling to idle, especially if rapidly, can cause the engine to die if the idle speed and idle mixture settings are fairly far off from where they should be. Many variables here, so no conclusive answers, but it definately can happen when the settings are off.

On the climb issue, that is a bit tougher. If you leave the throttle fully open and let the RPM and airspeed get too low, I can see a case where you become too lean, especially with a 40* up angle with a carb. At these speeds, there is no G force to help keep the fuel in the bowl level. Carbs don't do so well at WOT and low RPM without accelerate pump enrichment. As you get to stall speed in these climbs, what is the RPM?

Not sure that I understand the point of the test of holding a 40* climb angle all the way to stall speed at WOT. This starts to get to something like a hammerhead and I have 0 experience with that kind of stuff. Maybe one of the aerobatics guys have experience with engine issues in these situations.

 

[dpansier]

I have downloaded the Dynon data but the spreadsheet is so enormous I don’t know how to make it useful to find what is happening. I suspect the fuel flow is dropping dramatically there.

For starters, I suggest uploading the Dynon flight data to the Savvy Aviation website and allow it to be viewed by the group here. Any abnormal parameters will be quickly identified.

 

[Snowflake]

Did the propellor stop turning? If not, the starter wouldn't help you anyway.

This sounds normal for a carburetor... The float bowl needs gravity to work, and gravity is pointed the wrong waynehen you're vertical.

 

[luddite42]

Sounds like you never had any formal aerobatic training. Pulling power to idle during the hammer pivot is totally wrong and unnecessary unless you really mangle all the inputs and find yourself starting to spin out of it. Reading in a book after the fact that this is not how to do a hammerhead is far from ideal to say the least.

That being said, you mention a low idle setting. If you pulled power to idle during the pivot, you'd have virtually no airspeed helping that lightweight Whirlwind prop continue to turn. So it stopped. This can also happen during spins with a low idle setting and a composite prop.

Aside from the training issue, these narratives also drive home why you should always try to do acro over a potential landing spot.

 

[WA85]

Low RPM / fuel flow, combined with a little bit of negative G on a carb'ed engine, can cause the engine to quit. Also if you have a light weight / low inertia prop, that can exasperate the issue. I have an IO-320 with a Catto prop, unloading the prop, at idle, during a stall or spin sometimes causes my engine to want to quit, but once airspeed is increased, the engine comes back online.

 

[oaklandaviator]

Hammerhead turns require full power all the way through the pivot, especially with a fixed pitch prop since so much thrust is lost at the low airspeed and the airflow is needed to help with the pivot. Very easy to lift the fuel off the bottom of the bowl.

As far as wiring up the starter so it won’t start with both mags on, personally I think that’s a terrible idea. A lightweight prop stops quickly and will take considerable speed to get it to windmill, and a lot of time and altitude. You definitely want to be able to hit the starter if it quits during any maneuvers and not have to turn off one of your mags. I strongly suggest changing this immediately.

 

[Jonnyb]

What’s the thinking behind only one mag when using the starter?

 

[mmcmanus]

Did you have carb heat on? Carb ice can bite you when least expected especially with throttle closed.

 

[lr172]

What’s the thinking behind only one mag when using the starter?

You only want to start via a mag with an impulse coupling and most planes only have one of those, so they always start on one mag. If you have lost your engine in the air, caution goes to the wind and you start on whatever is available at that instant. Some folks diasble the starter until the non impulse mag is shut off to avoid accidently starting with both and this story is a good example of why that is not a good idea.

 

[Dan 57]

Top of the first ever stall turn.

Done plenty of those, though my ship has a CSP. Never had an issue with fuel not reaching the carb, even when botched as having pulled more than the 90° vertical. With the e-pump off that is.
Those stall turns/hammerhead on our modestly powered RVs are of pretty short duration, and if pulling say 3G from the horizontal, will only give a few seconds until the rudder will be kicked, maintaining full power for a left one that is. A stall turn to the right is doable, but a more difficult maneuver, and is best acquired thru the right training.
One of the many advantages of a carb is the low pressure it needs, and the Avstar is no exception with 0.5psi.

 

[luddite42]

A stall turn to the right is doable, but a more difficult maneuver, and is best acquired thru the right training.

Of course unless you're flying a competition sequence that requires a (otherwise downwind) hammer pivot on a day the wind is really kicking, one need not bother attempting hammers in the opposite direction. But this would involve an exception to the rule of maintaining full power through the pivot. Pivoting in the opposite direction does typically require pulling some power off at the right time so that the propwash doesn't fight the yaw so much. And it also helps to slide the airplane on the upline for more rudder pivot authority. But again no reason for any of this outside the competition world. Sorry thread drift.

 

[JonJay]

You only want to start via a mag with an impulse coupling and most planes only have one of those, so they always start on one mag. If you have lost your engine in the air, caution goes to the wind and you start on whatever is available at that instant. Some folks diasble the starter until the non impulse mag is shut off to avoid accidently starting with both and this story is a good example of why that is not a good idea.

Additionally, the impulse coupling retards the spark to insure it doesn’t fire early producing a kick back. The impulse also speeds up the mag “kicking”’it for a hotter spark.
My Bucker has impulse on both mags, but you still only start with one mag as the mag timing can be slightly off between each other.

 

[RNB]

Quite being so melodramatic with the thread title for a start. Your engine did not fail.
Does your checklist confirm engine runs at idle on the ground?

 

[oaklandaviator]

A continuation of my thoughts on the starter wiring:

We have the same system on my wife’s RV-3. We just leave the right mag switch off for normal ground starts. However I’ve started it many times with both switches on and it’s never kicked back. And it runs much better and easier to keep running after start with both of them already on.

I would never, and I mean never, wire the starter not to work with both mag switches on. That’s a very bad idea. If you’re that worried about it then get a normal key switch which can be set to disable the right mag while the key is in the start position but both mags are instantly on when you return the key to the run position.

(Edited to delete incorrect info correctly pointed out below. Thanks, Guys!)

 

[lr172]

However I’ve started it many times with both switches on and it’s never kicked back. Probably because the left with the impulse coupling is firing first anyway. And it runs much better and easier to keep running after start with both of them already on.

The impulse coupled mag has a 15-20* retard (less advance) from normal firing at low RPM. This means that it fires AFTER the non impulse mag. Starting without retard increases the possibility of a kick back, but does not gaurantee it. kickbacks at 25* of advance are the exception, not the rule. However, if you keep doing that way, it WILL kick back eventually. Just flip on the other mag as soon as it kicks to get the benefit..

 

[JonJay]

A continuation of my thoughts on the starter wiring:

We have the same system on my wife’s RV-3. We just leave the right mag switch off for normal ground starts. However I’ve started it many times with both switches on and it’s never kicked back. Probably because the left with the impulse coupling is firing first anyway. And it runs much better and easier to keep running after start with both of them already on.

I would never, and I mean never, wire the starter not to work with both mag switches on. That’s a very bad idea. If you’re that worried about it then get a normal key switch which can be set to disable the right mag while the key is in the start position but both mags are instantly on when you return the key to the run position.

The impulse retards the timing, not the other way around. The non impulse mag will fire first. When you time your mags, you make sure the pulse has fired, then back off to set timing.
You still risk a kick back even though you have never had one. The non impulse mag will fire before tdc as it is timed to do.
This isn’t a risk at higher rpms.

(Typing at same time as above….)

 

[oaklandaviator]

The impulse retards the timing, not the other way around. The non impulse mag will fire first. When you time your mags, you make sure the pulse has fired, then back off to set timing.
You still risk a kick back even though you have never had one. The non impulse mag will fire before tdc as it is timed to do.
This isn’t a risk at higher rpms.

(Typing at same time as above….)

You are absolutely correct. Quick typing and thinking. I still haven’t had it kick back but it is a distinct possibility. Thanks for the quick correction!

 

[Cumulo]

Been there, done that. Muddy plowed field near Romeo Michigan as a teen student pilot about a century ago. Slow flight -chopped the power - instant Aeronca glider. No damage.
I am short on advice about your particular situation, but engine stoppage is a possibility with low airspeed, chopped throttle and especially unusual attitudes. In your case, just make sure you can crank the engine a blade or two to get it back online in flight.

 

[DanH]

Top of the first ever stall turn.

Left rudder. Yaw established. Throttle to idle. Propellor stops.

Fail to restart in air.

Land in paddock.

I think you merely flooded it. Good lesson.

There is a strong tendency to push at the top of a hammer if the airplane feels like it's going over on its back. Don't do that. If it starts over backwards, center the controls, including the rudder, and wait. It will settle nose down eventually. Going over while stalled with full rudder (the classic botched hammerhead) is the entry to an inverted spin.

A flooded restart with the throttle at idle probably won't work. If it happens again, push the throttle in, then crank. Does two things. One, it's flooded, so it needs air to get into the combustible range. Two, if the prop hasn't stopped, it will help keep it windmilling.

 

[jrs14855]

Stall Turns, Hammerheads in the US should not be attempted in an RV unless equipped with inverted fuel system. RV's are not approved for tailslides and one will eventually do a tailslide attempting these with no inverted fuel.

 

[Jerry Fischer]

Did the propellor stop turning? If not, the starter wouldn't help you anyway.

This sounds normal for a carburetor... The float bowl needs gravity to work, and gravity is pointed the wrong waynehen you're vertical.

Bingo!

 

[blaplante]

I'm having trouble from the description visualizing the aircraft attitude. "Stall Turn"? So a coordinated accelerated stall? But then comments about hammer heads, knife edge, etc... ?

 

[RV8iator]

Stall Turns, Hammerheads in the US should not be attempted in an RV unless equipped with inverted fuel system. RV's are not approved for tailslides and one will eventually do a tailslide attempting these with no inverted fuel.

That's just not correct.

 

[Gash]

Stall Turns, Hammerheads in the US should not be attempted in an RV unless equipped with inverted fuel system. RV's are not approved for tailslides and one will eventually do a tailslide attempting these with no inverted fuel.

I really gotta chime in here. Having flown hundreds of hammerheads (stall turns) in an RV without an inverted fuel system, this statement, although well-intentioned, is not based in fact. If flown correctly, any aerobatic RV can fly beautiful hammerheads with no ill effects on the engine or tail feathers. As stated by others here, keep the power up. Going to idle would be a mistake. Also, find the airspeed at which your airplane pivots about the yaw axis with application of full left rudder. Try 50 knots or so for starters and see how it feels, but definitely do not wait until you're at zero airspeed. Remember, you do need airflow over your control surfaces. Also be sure to use elevator and aileron judiciously to counteract the effects of propeller torque.

Alright, that's all on the subject of hammerheads. Get some dual coaching and go have fun.

On the engine stopping, it's either fuel, air or spark right? I think air and spark have been ruled out here. What's left is the fuel situation with low idle, too lean, etc. Get that ironed out and you'll be back in business with no problems.

 

[WillG]

Possible issue.
Carburetor Ice, had it happen in pattern, went to idle landed ran up fine.
If using what Vans sells or sold its not adequate.
Get good carb heat muff that draws heat.

 

[kens_cockpit]

For starters, I suggest uploading the Dynon flight data to the Savvy Aviation website and allow it to be viewed by the group here. Any abnormal parameters will be quickly identified.

Wilco

 

[kens_cockpit]

Sounds like you never had any formal aerobatic training. Pulling power to idle during the hammer pivot is totally wrong and unnecessary unless you really mangle all the inputs and find yourself starting to spin out of it. Reading in a book after the fact that this is not how to do a hammerhead is far from ideal to say the least.

That being said, you mention a low idle setting. If you pulled power to idle during the pivot, you'd have virtually no airspeed helping that lightweight Whirlwind prop continue to turn. So it stopped. This can also happen during spins with a low idle setting and a composite prop.

Aside from the training issue, these narratives also drive home why you should always try to do acro over a potential landing spot.

 

[Dan 57]

Wilco

a better alternative (and free...) being FlySto as not only can you see all your engine and sensor data, but also at your flight data, and the way you flew, replay in Google Earth, etc.

 

[kens_cockpit]

Read hammerhead for stall turn

I'm having trouble from the description visualizing the aircraft attitude. "Stall Turn"? So a coordinated accelerated stall? But then comments about hammer heads, knife edge, etc... ?r

 

[kens_cockpit]

The propellor stopped.

Did the propellor stop turning? If not, the starter wouldn't help you anyway.

This sounds normal for a carburetor... The float bowl needs gravity to work, and gravity is pointed the wrong waynehen you're vertical.

 

[kens_cockpit]

Quite being so melodramatic with the thread title for a start. Your engine did not fail.
Does your checklist confirm engine runs at idle on the ground?

Felt dramatic at the time. Still does now. But your observation is correct. Changed the thread title to be more accurate.

Checklist did and does confirm the engine runs at file on the ground.

 

[jakej]

A continuation of my thoughts on the starter wiring:

We have the same system on my wife’s RV-3. We just leave the right mag switch off for normal ground starts. However I’ve started it many times with both switches on and it’s never kicked back. And it runs much better and easier to keep running after start with both of them already on.

I would never, and I mean never, wire the starter not to work with both mag switches on. That’s a very bad idea. If you’re that worried about it then get a normal key switch which can be set to disable the right mag while the key is in the start position but both mags are instantly on when you return the key to the run position.

(Edited to delete incorrect info correctly pointed out below. Thanks, Guys!)

“I would never, and I mean never, wire the starter not to work with both mag switches on.”
An inquiring mind needs to know WHY ? It is wired according to page Z-34 designed by a guy called Bob Nuckholls - have you heard of him ?

 

[oaklandaviator]

“I would never, and I mean never, wire the starter not to work with both mag switches on.”
An inquiring mind needs to know WHY ? It is wired according to page Z-34 designed by a guy called Bob Nuckholls - have you heard of him ?

For the very reason this thread was started. I have had a slightly misadjusted Ellison quit during spin entries during an airshow, on rollout with other planes right behind, and several other times. I’ve had dual p mags quit below their generator speed while doing stalls in a brand new RV-8 that had a wiring issue. I’ve had a Rotax 912 quit in a Titan Tornado while at the top of a loop while trying to figure out the best method to do aerobatics in it. Each of these cases was rectified by quickly reaching up and hitting the starter. I would never wire the starter to not engage with the ignitions on for this reason.

Much easier to have a checklist for initial start that says to leave off one mag than to remember to turn off a mag while you’re inverted with no engine after a botched maneuver…

My tone is not meant to be confrontational, but no matter who suggested I wire a starter to not engage unless I remembered to turn OFF a mag, I just wouldn’t listen to because of my own experiences. As I said before, if someone was that worried about having the right mag off in all circumstances during engine start I would suggest a standard key switch that does it internally.

 

[jakej]

For the very reason this thread was started. I have had a slightly misadjusted Ellison quit during spin entries during an airshow, on rollout with other planes right behind, and several other times. I’ve had dual p mags quit below their generator speed while doing stalls in a brand new RV-8 that had a wiring issue. I’ve had a Rotax 912 quit in a Titan Tornado while at the top of a loop while trying to figure out the best method to do aerobatics in it. Each of these cases was rectified by quickly reaching up and hitting the starter. I would never wire the starter to not engage with the ignitions on for this reason.

Much easier to have a checklist for initial start that says to leave off one mag than to remember to turn off a mag while you’re inverted with no engine after a botched maneuver…

My tone is not meant to be confrontational, but no matter who suggested I wire a starter to not engage unless I remembered to turn OFF a mag, I just wouldn’t listen to because of my own experiences. As I said before, if someone was that worried about having the right mag off in all circumstances during engine start I would suggest a standard key switch that does it internally.

I understand, no offence meant here. I had a plane certified with key switch with the same 0-320 engine with Hartzell FP prop doing various aeros ( always above the minimum 3000ft agl as required here) including Stall turns, 1/2 Cuban 8’s, 1/2 reverse Cuban 8’s without any engine stoppages. Aero sequences were after the HASEL checks were done.
If it were my plane this aircraft would have RH Mag OFF at the top of the emergency Engine Out Check List before -
Fuel On Fullest Tank
Fuel Pump On
Mixture RICH
Carby Hot (if appropriate)
Etc, etc.

 

[luddite42]

There is a strong tendency to push at the top of a hammer if the airplane feels like it's going over on its back. Don't do that. If it starts over backwards, center the controls, including the rudder, and wait. It will settle nose down eventually. Going over while stalled with full rudder (the classic botched hammerhead) is the entry to an inverted spin.

I'll only point out that in reality it's impossible to spin out of a hammer unless you really duff it as only a rank newbie could possibly do - as in for some reason adding FULL or very near full forward stick during the pivot and hanging onto that input along with the full rudder input while the airplane departs. Half elevator won't do it. A proper pivot only requires an inch or two of forward stick movement to oppose the gyro precession and it doesn't matter how far on your back you get if that's all the forward stick you're holding. No chance of a spin in that case. Nothing to worry about of course for anyone who's had a little quality acro/spin training. But for those who refuse, hope you at least understand (and practice) that pulling power and neutralizing all three controls will recover any possible spin departure situation in an RV. This is no substitute for proper training though.

 

[JonJay]

For those that say the starter should always work with both mags on;
The standard ACS key switch that was, and maybe still is, shown in Vans wiring diagrams disables the non impulse mag on start. The ACS key switch is a standard in thousands of aircraft.
I don’t see an issue with that in any scenario other than an impulse mag failure, in a way that it causes the other mag to be inoperative, along with a stopped prop. I guess it could happen but the odds seem very low.
What am I missing?

 

[DanH]

What am I missing?

Nothing Jon. It's mostly preference. I prefer a pair of SPST mag switches, with an entirely separate start circuit. Simplify and add lightness.

Back when I had standard Slicks it was one switch ON while cranking. The last 1000 hours have been with the EDIS system, which fires about 5 BTDC at cranking RPM, so both are ON. Going forward, it will become the standard as more users go to some form of dual EI. For example, I imagine the new electronic Slicks will incorporate a software cranking retard.

 

[lr172]

For those that say the starter should always work with both mags on;
The standard ACS key switch that was, and maybe still is, shown in Vans wiring diagrams disables the non impulse mag on start. The ACS key switch is a standard in thousands of aircraft.
I don’t see an issue with that in any scenario other than an impulse mag failure, in a way that it causes the other mag to be inoperative, along with a stopped prop. I guess it could happen but the odds seem very low.
What am I missing?

Some folks wire it such that the starter will NOT operate with one of the mag switches in the on position. VERY diiferent than the sterter key disabling one mag. If your engine just died and you are tumbling to the ground at an alarming rate, in the panic, you may not remember that you have to turn off one of the mags for the starter to work and keep[ wondering why the starter won't engage when you press the button. Very few people think clearly in a panic situation, so don't paint yourself into a corner. A single kick back is a small price topay for being able to restart your engine in such a situation.

 

[jrs14855]

For those that say the starter should always work with both mags on;
The standard ACS key switch that was, and maybe still is, shown in Vans wiring diagrams disables the non impulse mag on start. The ACS key switch is a standard in thousands of aircraft.
I don’t see an issue with that in any scenario other than an impulse mag failure, in a way that it causes the other mag to be inoperative, along with a stopped prop. I guess it could happen but the odds seem very low.
What am I missing?

Bendix switch is the same.

 

[GlennBfromOz]

Some folks wire it such that the starter will NOT operate with one of the mag switches in the on position. VERY diiferent than the sterter key disabling one mag. If your engine just died and you are tumbling to the ground at an alarming rate, in the panic, you may not remember that you have to turn off one of the mags for the starter to work and keep[ wondering why the starter won't engage when you press the button. Very few people think clearly in a panic situation, so don't paint yourself into a corner. A single kick back is a small price topay for being able to restart your engine in such a situation.

I am in complete agreement with this view.

I know a little of this event, and my intent is not to criticise but hopefully to help prevent a recurrence...

The engine in all likelihood stopped because of the combination of a lightweight prop, a carbed engine and throttle closure while running out of airspeed. That can happen. But what turned it into something more serious was the failure of the starter to turn when expected. The best move the pilot made that day was, when that situation occurred, to admit defeat before getting too low and to concentrate on making the forced landing work.

I have the greatest respect for both Mr Nuckolls and the actual installer in this aircraft. But I can't find a way to accept that this is an appropriate way to wire the starter. It's setting the pilot up for failure when he needs it to function and, in the heat of the moment, it refuses to do so.

A keyswitch prevents both kickback and failure to crank, by simply earthing the non-impulse mag. This works fine for the majority who use it. But if the builder prefers separate mag and starter switches, why could this function not be replicated? Either use a double pole switch for the starter, or a separate relay, going to the P-lead. So the starter inhibits the mag, and not the other way around.

I've already suggested to the OP that he have his aircraft modified, so this can't bite him again.

Glenn

 

[lr172]

I am in complete agreement with this view.

I know a little of this event, and my intent is not to criticise but hopefully to help prevent a recurrence...

The engine in all likelihood stopped because of the combination of a lightweight prop, a carbed engine and throttle closure while running out of airspeed. That can happen. But what turned it into something more serious was the failure of the starter to turn when expected. The best move the pilot made that day was, when that situation occurred, to admit defeat before getting too low and to concentrate on making the forced landing work.

I have the greatest respect for both Mr Nuckolls and the actual installer in this aircraft. But I can't find a way to accept that this is an appropriate way to wire the starter. It's setting the pilot up for failure when he needs it to function and, in the heat of the moment, it refuses to do so.

A keyswitch prevents both kickback and failure to crank, by simply earthing the non-impulse mag. This works fine for the majority who use it. But if the builder prefers separate mag and starter switches, why could this function not be replicated? Either use a double pole switch for the starter, or a separate relay, going to the P-lead. So the starter inhibits the mag, and not the other way around.

I've already suggested to the OP that he have his aircraft modified, so this can't bite him again.

Glenn

All excellent advice and commentary here. While FAR more remote of a possibility, mags can die in the air. I would prefer the option to start on the non impulse mag if that is my only option. This provides an option not found with keyed starters and adds to safety margin IMHO. Also allows you to start on the ground in a remote location when the impulse mag has died in order to get home. There is a poster above who routinely starts on a non impulse mag. Kick backs are the exception not the rule with stock timing, so why not leave the option open? Its not that hard to teach yourself how to set up your plane for a start. We are all pretty smart, so why all the steps to prevent errors? Just a different opinion.

 

[skylor]

All excellent advice and commentary here. While FAR more remote of a possibility, mags can die in the air. I would prefer the option to start on the non impulse mag if that is my only option. This provides an option not found with keyed starters and adds to safety margin IMHO. Also allows you to start on the ground in a remote location when the impulse mag has died in order to get home. There is a poster above who routinely starts on a non impulse mag. Kick backs are the exception not the rule with stock timing, so why not leave the option open? Its not that hard to teach yourself how to set up your plane for a start. We are all pretty smart, so why all the steps to prevent errors? Just a different opinion.

However, if in flight with a stopped prop, once the starter gets the engine turning over aerodynamic forces will keep the prop turning (at least for a short period of time) after release of the starter switch and the non-impulse mag will then still be able to light-off the engine.

Skylor

 

[lr172]

However, if in flight with a stopped prop, once the starter gets the engine turning over aerodynamic forces will keep the prop turning (at least for a short period of time) after release of the starter switch and the non-impulse mag will then ste be able to light-off the engine.

Skylor

Good point

 

[RV-9erA]

Does your carburetor have the "bullet proof" Blue Epoxy upgrade float kit? I had two similar experiences with two different engines at high deck-angle climbs, which turned out to be sunken floats. After that, I will never fly a carbureted engine without this upgrade kit. Already used two of my unknown number of lives getting the airplane back to the airfield. If the carburetor has this upgrade kit, the name plate should be an "F" stamped on it.