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Can the wrong primer cause engine stoppage?

bobmarkert

bobmarkert

Well Known Member
Is it possible that using the wrong paint primer can affect engine reliability? (kidding)...... BUT..... my engine quit at the 3 ½ turn point in a 6 turn spin. That got my attention but…… when the prop did not immediately start to windmill when I stopped spinning I was surprised….. and went for the boost pump and starter. I have a high compression IO-375 and a low mass Whirlwind 200 RV prop. Does anybody have any insight if this was normal behavior? I subsequently did a 4 spin turn with no issues and it kept running. Here is a link to the video.

https://www.youtube.com/watch?v=W4BH2tp_e2Q

Thanks
Bob
 
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I think you would need 160-170 kts to windmill a fresh IO 375.

With an IO-XXX anything there should only be a boost pump, no primer at all, I think....

As to why it died in the spin, perhaps the idle RPM is a touch low, or the mix too rich for idle at 10K feet.
 
F1R said:
As to why it died in the spin, perhaps the idle RPM is a touch low, or the mix too rich for idle at 10K feet.
Click to expand...

Another potential is that with partial fuel, the fuel goes to the outside portion of the tank away from the pickups and the engine starves. This is actually pretty common with prolonged spins, although I don't typically see it until >5 turns.
 
ChiefPilot said:
Another potential is that with partial fuel, the fuel goes to the outside portion of the tank away from the pickups and the engine starves. This is actually pretty common with prolonged spins, although I don't typically see it until >5 turns.
Click to expand...

What was your fuel load? If below half or so this is a real possibility
 
1/2 tanks

Dan that may be the answer. I had half tanks. I think the 6 turn spin was on the right tank which has a normal fuel pickup. The fuel
may have moved away from the pickup in a spin. The subsequent spin was on the left tank which has a flop tube which may have followed the fuel as it was moved outboard by the centrifugal forces. I'm excited now, another reason to go flying and flight test these possibilities
 
RVDan said:
What was your fuel load? If below half or so this is a real possibility
Click to expand...

Mine was about 10 gallons a side, so less than half. I knew this was a distinct possibility so it wasn't a surprise. It happened frequently during spin testing (which I did a *lot* of both during and after phase one) and is pretty much a non-event.

The difference between my situation and Bob's is that my prop (Hartzell BA) never stopped windmilling.
 
Fuel Starvation?

The fuel starvation idea doesn't make sense to me because of the fuel that is still in the lines. It would take quite a while to deplete the fuel remaining in the lines even if the pickup started sucking air, especially at idle.

Also, next time you are out doing spins you might want to point your camera out the back so you can see what the tail is doing during your spin. Once I saw how much the tail was flexing I decided not to do anymore spins.
It may have just been my -8 and its CG but I assume they would all do it.
Like you said, another excuse to go fly!
 
SuperDave said:
Also, next time you are out doing spins you might want to point your camera out the back so you can see what the tail is doing during your spin. Once I saw how much the tail was flexing I decided not to do anymore spins.
Click to expand...

Why use a camera? Just turn around and look :) Yep, the tail shakes some but nowhere near as much as the tail on a 152/172 does during a spin. It's not something to be afraid of, IMHO, if you've built per plans.

On the other hand, if the tail shaking is concerning, don't look at it as you pull the mixture when shutting down the engine. The wet dog shake of the four cylinder lycomings make the tail shake just as much.
 
Windmilling prop

Last year when my engine quit because of an electrical short my prop kept windmilling until I slowed the aircraft down to loose altitude then it quit turning. I even increased the speed some on landing and still the prop did not turn. They claim you can glide farther like that so it can be a good thing!
Oh by the way I liked your video of the spins.
 
Engine stoppage

I've owned three Pitts s1's and two of the three had a flop tube. Didn't like them because of loss of fuel in certain conditions, stiffness with age and then the tank had to be loaded with more fuel to compensate. The bright spot was my last S1 which had a Gordon Price tank with a built in header tank(2 gal). No matter what I did, never a sputter, ever and no flop tube. I think it's the way to go but nowhere to put it in a RV, I think. My S1 always flew great with about four to six gallons of fuel, very light. I'm sure the RV would fly great with the same amount (over the field only) of fuel. I don't like wing tanks with multiple turn spins. We always flew the Decathlon with quarter tanks or less.
Fifteen turn spins upright and inverted, no fuel pressure loss. It had a header tank.
Anyway, my two cents... John
 
ChiefPilot said:
Why use a camera? Just turn around and look :) Yep, the tail shakes some but nowhere near as much as the tail on a 152/172 does during a spin. It's not something to be afraid of, IMHO, if you've built per plans.

On the other hand, if the tail shaking is concerning, don't look at it as you pull the mixture when shutting down the engine. The wet dog shake of the four cylinder lycomings make the tail shake just as much.
Click to expand...
I would love to turn around and look at the tail while spinning but my 51 year old life-abused neck won't allow it anymore:)
I think what really got my attention was the fact that I happened to see the tail doing its thing right after I did the inspection for the tail spar cracks when the SB came out. I'm probably just getting wimpier (and maybe wiser) as I get older.
 
Aft facing camera

I had a camera facing aft in this video:

https://m.youtube.com/watch?v=P7YYpf5_xTE

It only captures a little of the elevator in a spin. Next flight I'll position it for a full view and let it spin its heart out and post it. I'll have a spoiler alert for those that just don't want to know------

Bob
 
From what I could see in the video your tail wasn't moving at all. In my plane the tail had the most movement at the initial stall when the buffeting was occurring. It would do it in a straight on stall also. My CG was well forward and maybe that was creating more of a load on the tail and the harsh buffet.
Maybe someone smarter than me can explain it.
 
The "primer" comment, in that situation, was hilarious. :)

bobmarkert said:
Is it possible that using the wrong paint primer can affect engine reliability? (kidding)...... BUT..... my engine quit at the 3 ? turn point in a 6 turn spin. That got my attention but?? when the prop did not immediately start to windmill when I stopped spinning I was surprised?.. and went for the boost pump and starter. I have a high compression IO-375 and a low mass Whirlwind 200 RV prop. Does anybody have any insight if this was normal behavior? I subsequently did a 4 spin turn with no issues and it kept running. Here is a link to the video.

https://www.youtube.com/watch?v=W4BH2tp_e2Q

Thanks
Bob
Click to expand...
 
RV8 tail shak during spin

As promised here is a aft view of my RV8 tail during a 5 1/2 turn spin. Judge for yourself how bad the tail is shaking. Part of the shake is the buffet of the airframe and camera mount so be sure to focus just on the tail.

My plane has 65 hrs TT and I can now see in the video where the draft is coming from. I’ll fix that tomorrow.

Tom “Strato” Spratt hung on pretty good during the loop.

P.S Tom's aircraft is featured as the September photo in the Vans 2016 calendar

https://www.youtube.com/watch?v=mZqIH2VUlWs

Bob
 
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grove gear

Carl, I do not have those strakes but I do have grove gear which has airfoil shaped legs with no further fairings needed. I'm not sure if that affects airflow over the tail
 
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