Engine Quits on Runway After Landing!!!?

My wife and I own an RV-9A that we slow-built in the 2001/2003 period. We have a little over 300 hours on the plane now (5 yrs + flying). The engine (160 hp D3G) came from an accident Piper and was completely disassembled and parts checked for specs, etc., o/h fuel pump, o/h of carb, rework of camshaft, exchanged crankshaft, all this by a reputable engine overhauler. The times on the Slick mags are unknown. So, the engine work was basically an engine overhaul, but handled like an IRAN. Engine had 600 hours SMOH at time of the IRAN, about 2600 TTSNEW.

The engine has been run on both avgas and mogas (91 and 93 octane) for the past 300 hrs. It has been very dependable except for some carb anomalies and I have had the carb in the shop for o/h twice. I believe that we can rule out any problem with the "normal" operation of the carburetor.

Recently, on three occasions, the engine has suddenly stopped running at the very end of the landing roll on our 2700' grass strip at our home base. It's not a good feeling......... Rather than mention all the theories that we have fielded here on the airport (a residential airpark) I would like some feedback from the group based on your theories or your experiences with phenomena similar to this. I will say that the cutoff events have come "out of the blue" at idle throttle after landing and that the engine runs the same as always in takeoff, climb and cruise modes. It's the last mile to the runway that has me on the edge of my seat. <G> The RV-9A "glider" is always throttled way-back on landing.

Thanks for any input.

Bill Deane
Hayesville NC RV9A

Bill,

Do you have any other details? How is your idle speed set? Is there evidence of a fuel leak? How about evidence of a carb float that sticks occasionally? Does this happen in humid weather, which might indicate carb ice?

Any chance, Bill, that your idle is set too low? In the air, the wind pushes the prop along, but when you roll out and the throttle is pulled back to the stop, it's too low to keep running.

Just thinking out loud...

Sounds like a lean idle mixture (car guy here, never worked on an aircraft engine). When the aircraft is in motion, the windmilling produces enough vacuum to keep the idle circuit working while also depleting the circuit of fuel. Once you slow way down, vacuum decreases and there's not enough fuel coming. Could be as simple as a mixture screw adjustment. Maybe a float adjustment.

Does it start right up again?

ff

do you use carb heat when landing? i have heard of a lyc doing the same thing with carb heat on, and with low idle and rich setting may cause this problem.

Does it start normally after it has died, or does it take some doing to get it going again?

Are you

running the boost pump on landing?

I'll take a stab.

While it could be many things and I don't claim to be an expert, I'd start with the simple things first. Is sounds like it could be going lean on the low end. When the engine is operating normally, do you get a rise of about 50 rpm when the mixture is pulled to idle cut off. If so, that should verify that you are rich of peak at idle. Any chance you have an intake leak. With the carb going on and off the engine a few times recently you may have adjusted the idle and mixture with a small intake leak.

Robert

What is the slope of the runway at the end, and are you doing any hard braking just before the end???

Have you been landing with tanks pretty low??

As Paul asked, what are the re-start results.

Had similar symptom a couple weeks ago caused by carburetor float problem and addressed by SB. See forum thread Lycoming Carburetor Float Failure

This is Bill again.

In about an hour you can see that we got several responses to my query. Many thanks for your input and interest in helping with this. In forty-three years of flying I believe this is the first time I have had an airplane behave this way, so again; thanks.

I intentionally left out several theories that we had already given some consideration, primarily to leave the playing field open for fresh thinking. Now I will answer some of the questions that you have raised.

1. Idle speed. I had just received the carb back from inspection/overhaul and installed it on the engine. With the engine still cold, the idle speed was between 5-600 rpm. I decided to adjust the idle screw one half of a turn inward, i.e. up in rpm. After flying the first time with this new adjustment (and finally getting the airplane back to the hangar) the idle speed in a warm or hot condition was running about 800 rpm, a little bit higher than I would like normally, but okay for now. Our conclusion here is that the problem does not appear to be a simple too-low setting of the normal idle speed which leads to a cutoff.

2. Sticking float or non-metal float (if SB not met). This problem evidenced itself both before and after the carb was overhauled. If there was any interference of the float units, surely they would have caught it. The service bulletin on the floats has been complied with.

3. Carburetor Ice. We have not completely ruled this out since this is summer and the humidity is always high in the southeastern US. On the other hand, we have flown the plane in these conditions for years and never have experienced this problem.

4. Restart Immediately? Nope. And this is puzzling. Is the fuel getting boiled and is vaporizing? Could carb ice finally be taking over the carb throat? Is the heat in the engine compartment causing the mags to cop out? (Both mags at the same time?!). I ran the plane up and down the airstrip for fifteen to twenty minutes yesterday PM trying to get it to show me a shutdown, but no luck. The oil was up to 200 F and CHT up pretty good, BUT NOTHING other than solid running on either mag, both mags all the time with the electric boost pump in the OFF position. When this has happened in earnest before, after about twenty minutes or so I could restart the engine more or less normally. Sometimes it is hard to tell whether you have overprimed or have starved a stopped engine.

5. Carburetor Heat for Landing? Always; regardless of the reputation for Lycoming engines resisting carb ice, I use the carb heat for the whole landing sequence.

6. RPM Rise at Shutdown? I looked for this when I shut the engine down after returning to the hangar. I did not see any rise. This may because our field is at 2000 foot elevation; I don't know. I do know that typically over the past five years flying this plane that the rpm has not risen as it is "supposed" to do at shutdown.

7. Slope of Runway. The runway is pancake flat and no hard braking is necessary to get the RV stopped. The surface is grass.

Any other ideas, please feel free to jump in. This is a safety issue that we are taking seriously. If you have some perspectives about the age and wear of the Slick mags, that might help. It appears that the mags may be in the vicinity of 900 hours now. This "could" be a factor, but they don't appear to be weak either at high or low rpm.

Thanks again.

Bill Deane
Hayesville NC RV-9A

Any obstructions in your airpath into the carb? Carb heat flap working properly and not blocking air inlet?

Speaking of the simple things, I had this happen when I forgot to richen the mixture before landing.

Does it happen in winter time or just on these hot summer days?

Does it happen more often when running mogas (or mixture of avgas and mogas) vs. straight avgas?

If your not getting a rise in rpm at shut down, I'd say your lean. How lean could be determined by enriching the low end. The 2000' field elevation would not prevent the rise in rpm. If the low end mixture was adjusted for sea level, if anything you would be a little rich on the low end at 2000', not lean. It seems logical to get the bottom end mixture set before you start chasing the other gremlins (which could still be present).

Robert

Some kind of induction leak that is making it run lean?

How about too rich?

Bill, it sounds to me like your engine is loading up after prolonged idle and perhaps too rich mixture. Try this: next time you land, try pulling the mixture about half way out to see it that has any effect. 2,000 foot elevation probably aggravates a possible rich mixture, too. Wood prop?

I think we're just throwing out possibilities, maybe we'll eventually hit on something!

Bill,

What are your FwF fuel lines like?

I had an un-insulated elbow in my line leading to the fuel flow meter when I first started flying.

In my forty hour phase 1 I experienced four or five engine stoppages, two while flying, and the rest right after rollout, just as you describe. One stoppage occurred on LONG final.

Prolonged flight at low airspeeds was the cause. It allowed heat to build up in the cowling.

After insulating that elbow I have not been able to recreate the stoppages.

Bill:
Just a question: On the ground with no airflow to help spin the prop, if your idle was set at 500-600 in an unrestricted state, what did the idle drop to when you pulled carb heat, or did you only check the RPM drop on engine run-up.
Terry, CFI
RV-9A N323TP

If you have some perspectives about the age and wear of the Slick mags, that might help. It appears that the mags may be in the vicinity of 900 hours now.

Click to expand...

Slick mags are required to be inspected every 500hrs.
There is a Service Bulletin out on Slick mags: SB3-08

Bill:
I see you're using slick mags. Just had a conversation with the IA whose shop handled my C210 for 20 years. Without prompting, he mentioned that he's seeing useful life on these to be in the area of 500-600 hours. He suggested I get at least one rebuilt before any problems surface, as I'm approaching 500 hours on my 9A. His thinking is that it's better to have a "newer"one along side one that will likely hit 600 hours next year.
Terry

My guess would be fuel boiling in the lines under the cowl. Upon landing, the air through the cowl is diminished greatly and combined with the Mogas leads to vapor lock. This would cause the hard to restart problem too. Insulating the lines if they aren't would help as someone previously suggested and running a tank of 100LL would help to prove or dispel this theory. Good Luck

engine quiting on roll-out

this has happened to me a couple of times in my training aircraft (DA20).

The engine is fuel injected.

It took a little cranking to get it going again so I could taxi off the active runway.

As a student pilot, its a little unnerving to have this happen.

The plane idles about 500 - 600 RPM after I do my run ups and about 1100 RPM on final with the throttle closed (cruise prop).

I'm always ready to add a pinch of throttle after touch down if I sense the engine is about to die.

I think the problem may be related to mixture.

Sounds like this problem is somewhat common.

Dave
-9A finish kit

Similar experience years ago

I had a Piper Archer II (owned it for 22 years) with a Lycoming O-360-A4M. On the first flight after the mechanic reinstalling the overhauled engine I was on short final to runway 19R at John Wayne Airport in Santa Ana, California well inside the airport boundary after crossing the San Diego Freeway. The engine started to die. I opened the throttle and got power back to make the runway then when I reduced power it started to die again. Ultimately it did die and I had to restart several times to get to my tiedown. My mechanic said that some component related to low power operation had fallen out of the carburetor. He fixed it (I do not know what he did) and the problem never recurred. It was a carb problem in my case but unfortunately I was not the mechanic and I do not know the details of the fix. Like your case, in flight at high power settings it was fine.

Bob Axsom

I second vapor lock

GregM said:

My guess would be fuel boiling in the lines under the cowl.

Click to expand...

I have seen this in our 6, in an injected Citabria and a W10 tailwind. Where heat soaked engine on a hot day- the engine quit at idle. Always after flying on a hot day with hot oil etc: since no more cooling air is moving through the engine. Have to play with the boost pump at that time on then off and carful not to flood on restart(especially injected). I try and get a high idle at restart with the engine running rough due to vapor locked lines/gas colator(whatever). Your fuel pressure may indicate zero at the time until you clear the vapor by turning boost pump on. worst seen was on the citabria at the restart(injected)Also seen it on more on the 10 with auto gas so mixed auto w 100LL that helped a little.

Vapour lock

Thats why I was asking if the boost pump was running on landing.

Having said that Paul did have the issue where we think the fuel lines were boiling the fuel after shutdown, forcing vapour back through the pump and VL'ing the boost pump.

It is quite possible for this to happen on landing too as the flowrate thru the pump is miniscule and the heat buildup under the cowl considerable.

So thats where i was going too..Then again this IS my favourite subjet..

Frank

Heat under cowl

could be considerable..I.e the hot engine heat soaks the fuel pump and lines..Not that the temprature climbs.

This could easily happen on rollout.

Frank

fuel bypass

nobody has asked if you have a bypass installed?. If you do not I would try this also.

I had much the same problem and discovered one side of the carb float was full of fuel. The engine would flood out when idling.

wfdeane said:

My wife and I own an RV-9A that we slow-built in the 2001/2003 period. We have a little over 300 hours on the plane now (5 yrs + flying). The engine (160 hp D3G) came from an accident Piper and was completely disassembled and parts checked for specs, etc., o/h fuel pump, o/h of carb, rework of camshaft, exchanged crankshaft, all this by a reputable engine overhauler. The times on the Slick mags are unknown. So, the engine work was basically an engine overhaul, but handled like an IRAN. Engine had 600 hours SMOH at time of the IRAN, about 2600 TTSNEW.

The engine has been run on both avgas and mogas (91 and 93 octane) for the past 300 hrs. It has been very dependable except for some carb anomalies and I have had the carb in the shop for o/h twice. I believe that we can rule out any problem with the "normal" operation of the carburetor.

Recently, on three occasions, the engine has suddenly stopped running at the very end of the landing roll on our 2700' grass strip at our home base. It's not a good feeling......... Rather than mention all the theories that we have fielded here on the airport (a residential airpark) I would like some feedback from the group based on your theories or your experiences with phenomena similar to this. I will say that the cutoff events have come "out of the blue" at idle throttle after landing and that the engine runs the same as always in takeoff, climb and cruise modes. It's the last mile to the runway that has me on the edge of my seat. <G> The RV-9A "glider" is always throttled way-back on landing.

Thanks for any input.

Bill Deane
Hayesville NC RV9A

Click to expand...

Engine Quits on Runway After landing!!!

Bill.............last post.

Many thanks to all of you who have made suggestions about my engine stoppages on rollout with my RV-9A. The ideas have been very helpful and I am indebted to you for them. Now for the application phase. Happy flying!

Bill Deane
Hayesville NC

Primer system leak...

Just a thought... Primer leaks can cause rich issues on the rollout. Not as apparent when engine is cold, or at high power settings.
Most likely a lean issue like others have posted, But worth a look.

HTH,
Chris

My Pitts S1 engine quit at the end of the landing roll several times after having some engine work done. Adjusted the mixture a little richer, and it cured the problem. Its an 0-360 with Ellison TBI.

Happened once

I had it happen once to me. Had a mechanic look at it and the idle mixture was too rich.

frankh said:

Thats why I was asking if the boost pump was running on landing.

Having said that Paul did have the issue where we think the fuel lines were boiling the fuel after shutdown, forcing vapour back through the pump and VL'ing the boost pump.

It is quite possible for this to happen on landing too as the flowrate thru the pump is miniscule and the heat buildup under the cowl considerable.

So thats where i was going too..Then again this IS my favourite subjet..

Frank

Click to expand...

If you land without your boost pump try landing with it on on your next flight.

If that solves the problem then that fact coupled with hard to re-start says vapor lock.

No matter what the problem find it and fix it before it happens at the worst possible moment during a flight.

mixture screw

One time my mixture screw baked out. Engine wouldn't run below 1200 rpm. Not fun to have the engine quit on short final. Take a look at your carb mixture idle screw.

joe

Daver said:

this has happened to me a couple of times in my training aircraft (DA20)....I think the problem may be related to mixture.

Click to expand...

Happened to me in a DA20 as well and in an instructional flight. My instructor leaned the engine at altitude and both of us forgot to enrichen it before landing. (Flight from KAEG to KLVS.) The prop stopped a couple of seconds after touchdown...

I will take a shot at this--I am assuming you have a fixed pitch prop.

You indicated that you get no rise at fuel cut off and that you originally had the idle set at 5-600 rpm. You also mentioned that since resetting the idle to 800 you have not experienced the problem.

I would speculate that you are too lean at idle and that this coupled with the low rpm results in an engine stoppage when you slow to the point that the prop is no longer "driving" the engine. I would enrichen the idle mixture until you get a 25-50 rpm rise at shut down and reset your idle back down to around 650---an 800 rpm idle in a 9 with a fp prop makes for longer "floating" landings.

My guess!!

Cheers,

db

Maybe engine fuel pump

This summer a friends Long EZ was doing basically the same thing. It turns out the diaphram in the engine fuel pump had started to harden which actually causes the pump to deliver higher pressure. Had pump checked at overhaul facility before pump teardown and they confirmed same problem. The carburator was actually being overpressurized and flooding the engine at idle. Check the TCDS for your engine and determine the proper fuel pressure and hook up a guage after the pump. Just something else to check. His engine also would not restart right after it quit. New fuel pump fixed problem.