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Declared an emergency today

Ed_Wischmeyer

Well Known Member
And my voice did quiver a little bit, so no macho points for me. (I did better with my last emergency 30 years ago...)

Haven't pulled the cowl off yet, so I don't yet know what happened, but here are the facts, hints, and recollections -- not all of which are guaranteed to be correct given the excitement of the moment
* RV-8, a real sweetheart to fly
* O-320 with high compression pistons, P-mags, ECI cylinders
* Last compression check about 8 hours ago, two jugs really good, two okay
* About 8 hours per quart of oil
* Cleaned the belly before takeoff
* 25 minute flight to my former airport to get gas
* Nice aileron roll enroute, nice 3G 360 degree turn to slow down before entering the traffic pattern
* The ATIS said landing runway 33R. Later on in the recording, it said runway 33R closed till further notice. Go figure.
* Groundspeeds 158 - 165 knots as I was vectored around
* Refueled, did not have fuel sampler to check the sumps
* Normal takeoff, but I wondered if I was maybe very slightly down on power. Still had screamin' performance, though
* About seven minutes after takeoff, heard something, felt something like a prop surge
* Declared an emergency, approach control suggested I turn back to former airport rather than continue to home field
* They instructed a right turn to keep me out of the restricted area off to my left that I completely forgot about in the excitement
* Felt several more very minor "prop surges" on the way back
* Power was indicating 25 x 2500, but groundspeed was 136 knots, a 20+ knot loss
* Winds calm on the ground, and apparently very light at low altitude, so the speed drop was probably power, not wind. In any case, I'd seen 158 knots in the same direction a few minutes earlier
* Came into the pattern high to make sure I had the field made, told tower I wanted pattern on the non-standard side so that the runway would be down sun (it was late afternoon).
* Was planning to do my normal end of the runway touchdown, but recalled that a mid-runway touchdown was a better plan in case of total power loss
* While reducing power, it was my impression that the RPMs did not come down as quickly as they normally do with MP reduction, but I'm not sure
* It was my impression that I might have had less prop drag than normal on base and final. In any case, the RV-8 slips really well and I easily had the runway made and plenty of runway left after touchdown, gentle wheel landing within a foot of centerline
* The crash trucks rolled as part of their SOP
* After landing, mag check was fine (P-mags)
* After landing, cycling the prop produced substantially more RPM drop than pre-flight. Then again, I've never cycled the prop after landing.
* Belly of the airplane was clean
* Front seat of the airplane was dry

Any guesses as to what happened? I have no clue at this point, and neither did the AI that I talked with on the phone. I'll pull the cowling tomorrow and see if there's anything obvious...
 
Before you pull the cowl, do a thorough preflight and see if you find anything amiss.

From your narrative, the only thing different from the flight to get fuel, and the flight afterward, was the fuel itself.

Maybe a red herring, but the last thing changed is usually the best place to look for the cause of a new problem.
 
Post-flight inspection showed nothing obviously wrong

No fluid leaks, and all the airframe pieces appeared normal. I'll give it a good going over tomorrow when there's plenty of sunlight, but the quick once-over showed nothing. I did switch tanks, just in case, but I don't think that did anything.
 
I was worried when I saw the title of your thread, Ed. Glad you got it down safe. 33R, former airport...? Where'd you move to?
 
Good job Ed - on the flying, and the report.

Which prop, and how many hours since it's last service?
 
Details

Currently based at Savannah (KSAV), my former airport is Mid-Coast Regional / Wright Army Air Field (KLHW).

Water in the fuel seems unlikely as it would not have caused a prolonged power loss to drop the airspeed 20 knots.

Don't know about the prop details other than it's a Hartzell constant speed. I'll look that up in a bit.
 
Just fishing...

While the cowl's off, check the governor control for security and proper position.

Might be worth pulling the governor and having it checked out, if you don't turn up anything else. The surge and the 2,500 rpm with low speed suggests that.

Incidentally - excellent decision-making in the air. Good job.

Dave
 
Power?

Good job Ed:

- Easy things to check -
Air filter clean, intact and not out of position,
Carb securely mounted to oil sump,
Screws tight on carb body halves,
Carb Venturi secure,
Exhaust system intact and unobstructed,
Mag timing,
Compression,
Appearance & resistance of spark plugs,
Gascolator/fuel filters,
Travel and rigging of throttle, mixture & prop controls,
Fuel flow at the carb,
Fuel tank vents,
Prop blades tight in hub,
Ground run with air filter removed and on each mag individually.

-Digging Deeper-
Remove valve covers to check valve movement and travel,
Boroscope cylinders and mufflers if installed,
Check oil filter and screens for metal,
Check fuel for quality and octane.

Don B.
RV 9 Rebuild in progress.
 
Glad you're OK

I'm sure you'll find the problem.
Just a couple of comments regarding how the emergency played out...
Fist, I'm surprised that after you declared, ATC was vectoring you away from a restricted area, especially if it was the shortest route to get you down safely. This should be your call (remember the Hudson River landing).
Second, even in a simulated emergency, many pilots I've reviewed will try to fly a standard pattern after loss of power. Most realize too late that they've given up altitude they need to make the pavement. When you declare and decide where you're going, the shortest distance is normally a straight line and sometimes, a landing straight-in with the wind is a better choice. You're PIC and once you've declared, you can and should deviate from any rule in order to ensure your safety. By the way, I've issued a few "maydays" over the past 40+ years and have never been asked to submit a report. That's the last thing anyone should be thinking about as they're trying to make other, good decisions.
Good job. Good post.
Terry, CFI
RV9A N323TP
 
Second, even in a simulated emergency, many pilots I've reviewed will try to fly a standard pattern after loss of power. Most realize too late that they've given up altitude they need to make the pavement. When you declare and decide where you're going, the shortest distance is normally a straight line and sometimes, a landing straight-in with the wind is a better choice.
...
Good job. Good post.
Terry, CFI
RV9A N323TP

I second that. I had my engine stopped in a Piper Pawnee some distance from the runway, but with lots of altitude (or so I thought). This happened after I had pulled a glider far into the mountains to the west, south-west of the airfield. My plan was to fly (glide) downwind as usual for runway 25 and if necessary make a few 360s at the base leg if I came too high.

What I did not take into account, and had no experience with, was the drag of the windmilling propeller on the dead engine. When just crossing the threshold of 07 I finally saw that I would probably not even make it to base 25, so I turned left about 120 degrees for base 07, crossed the extenden to bleed of some alt and turned back to 07 (7-8 knots downwind) at about 45 degree angle with good alt and set full flaps. I straightened up above the runway and touched down at the middle of the runway, with enough speed to roll off onto the taxiway. The runway is 800 meters.

In hindsight there were no way I would have made it to 25, even though I was initially sure that I would have lots and lots of altitude. If it happens again I sure will simply head straight for the nearest runway, and if that runway is downwind from me, I sure will plan for a down wind landing initially.
 
More details

Good comments all.

I over flew the runway at altitude so the pattern kept me within gliding range at all times. (I learned to fly on the east coast and no power patterns were standard.) Even if the runway was aligned with landing direction, I still would have flown a high pattern because those are more familiar and provide more options.

The edge of the restricted area was parallel to route of flight, so staying out was not an issue. It's a live fire artillery range, so going through it was not necessarily my best choice. And I heard the guns going off while I was refueling.

Since the engine was not rough, that probably means it's not an individual cylinder as pointed out, so that suggests fuel or induction blockage or fuel contamination. A friend not on this post also suggested carb ice. Relative humidity at KLHW was 75%, temperature was 58. When I left KSAV 45 minutes earlier, it was 59 and 55%.

I was on the ground for maybe 15 minutes. If I'd picked up some ice on descent, if it didn't melt, and I picked up more taxiing out... . Dunno.
 
According the the pop-out graph in this link it seems you were in the perfect range for serious icing.

http://flighttraining.aopa.org/students/presolo/skills/carbicing.html

Chunks breaking off would explain the prop burble periodically and low power but no roughness.

I had icing on a 182. I retrimmed a couple of times as I was losing altitude slightly, then noticed decreasing airspeed so pushed throttle, then reached full throttle and not going so fast. Thought a minute (what the ****??) and pulled the carb heat and WHAM - full power climbing like a rocket.

Better have a mayday than a sad report and thanks for sharing you make us all smarter. OK, at least , me. Good piloting!!
 
Ed, you report 25-2500 with a large speed loss. Would 25" have been normal for the altitude and throttle position at that time?
 
Ed, nice job. Nick here, in Prescott. Been following thread in last few days about minimal heat on the original muff from Van. If this turns out to be ice, you might plumb more heat to the carb. I have only been getting 20 rpm drop on my 9A with the stock heat. But, as you know, our humidity is not what you have over there. Glad you had nothing bent. Cheers!
 
25 squared is normal cruise

There's hangar space available, so today's plan is to check the air and fuel filters, gascolators, and take a reading on how much rpm drop I get with carb heat on the ground.

One lesson I'm learning is that I've become desensitized to carb heat over the years, especially flying lycomings and lots of low humidity flying. Maybe others can learn from this...
 
In our Mooney, (Lycoming O-360) I've picked up carb ice surprisingly quickly (just a couple of minutes) on the ground under the right conditions. A couple of times it has happened flying in light drizzle. The Mooney has very effective carb heat so it has not been a problem as long as you notice it.

With this experience, there was no way I was going with Van's mickey mouse carb heat system on our -8. Van's instruction sheet indicating that one should use it as a preventative measure and not expect it to melt carb ice cinched that one...

I installed a Robbin's Wings heat muff and closed off the heat box flange so that when activated all the air is pulled through it. It gives a good RPM drop and increasing carb temperature on the ground but I haven't had the chance to try it out on real ice yet.

The problem with carb ice is if it does cause you problems, by the time you land and try and diagnose it, the ice has melted and disappeared...

Good luck in trying to diagnose your issue...
 
Ed, do you have electric flaps on the stick? An inch of flaps would slow you down. Could explain the A/S drop, but obviously not the engine sound changes.
 
I'd put money on carb ice. The prop would surge depending on how severe it is. There will be no evidence of it later, just frustration looking for the cause.

That being said, check everything already mentioned.

Been there, seen it. Engine quit at 9500' restarted at 5500', landed in an emergency, no smoking gun. Called a very smart mech at home field, he concurred, carb ice, took off flew home.
 
Carb Ice Detector

I've got an ARP carburetor ice detector on my Cessna 180, and it works well. The light only comes on when there's actual ice, and goes off when the ice is cleared.

Aircraft Spruce sells them.

My only connection is that I'm a very grateful owner of this device.

Dave
RV-3B, now on the tanks
 
Surging prop and power loss

Ed,

Don't discount looking at the prop if it is a cs hartzell. I had the same issue about 5 months ago (no mayday or emergency declaration though). The short story was the prop hub "crapped-out" and was red tagged by the prop shop in The Chicagoland area. Installed new prop and it runs like a champ. Good luck! I do hop for your sake and your wallets it's only as simple as a little carb ice.
 
And the answer is...

Came out to the airport to see what we could see.

Pulled the prop through eight blades, with good compression on all, some better than others.

Started the engine and it didn't seem quite right.

Let it warm up a bit, carb heat gave a 100 RPM drop.

Prop control again showed more RPM drop when pulling the prop lever back, noticeably slow to regain RPM with he lever back forward.

Mag check (p-mags) was fine post flight yesterday. But just now, the left p-mag was completely dead. Kaput. No va.

No obviously loose or broken wires on the mag or the ignition switch. Pulling the pmag circuit breakers had no effect with the engine running.

Now to figure out how to pull the mag off. Anybody familiar with those? 912 665-2969.

Thanks

Ed
 
You've probably thought of this, but just in case: try everything you've got in your toolbox before taking apart baffles, oil cooler, etc... Crow's foot wrenches, open ended wrenches, all different lengths of extensions on a socket wrench, etc. I've found a lot of the time a break and a cup of coffee is enough for me to come back and see it from another angle and realize "hey, I can get there from this side instead!"

Glad to hear you got it back on the ground safely and the problem is getting identified...
 
I am not trying to be critical nor create thread drift. But this seems to be an opportune time to draw reference to this

http://www.cnatra.navy.mil/pubs/folder5/T34C/P-330_CH9.pdf

Chapter 8 describes the emergency landing pattern, not only used for engine out situations but also for precautionary landing in the case of a rough runner/partial power situation. The key concept is if you have a rough runner, use the available power to climb to a position to where you can glide to the high key position. From there there is no question about whether you will make the field.

The T-34 is close enough to RV's in flight characteristics that this is a good guide. If you take the time to understand the concepts, it is easy enough to learn all of the correct parameters to use in an RV. Then practice practice practice.

This is a very comprehensive flight instruction that provides an exceptional reference for any one that wants to be a better, safer pilot.

Nice Job Ed and hope you find a correctable cause.
 
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Done!

My friend with smaller hands got that puppy loose.

Have not checked the link yet (thanks!) but that's more or less what I did by staying high and entering the pattern from above, high final so the runway was assured.

Lots of lessons learned here, and thanks for all the comments, suggestions, and inputs.

The last thing to do is, on the test flight, make sure that nothing else is wrong!!
 
But wait, there's still more!

Had a great chat with Brad at emag. The mag failure is inconsistent with the large power loss. But he suggests that since I'm sending one back, I might as well send both back to be checked.

So carb ice is still in play as the major factor with the mag as an interesting but valid red herring.

Stay tuned!
 
So carb ice is still in play as the major factor with the mag as an interesting but valid red herring.

If 25-2500 is normal for that altitude and throttle position, I would discount carb ice. I don't think you could lose 20 knots worth of power due to icing and not see a drop in manifold pressure pressure.
 
More to come

Dan, agreed.

And it's also the case that the prop response during the runup this morning was sluggish, so there's more going on than just ignition.

So to summarize this mechanical soap opera:
* Had an event in flight that seemed like a prop surge, with several minor follow-ons
* Groundspeed loss after the event was about 20 knots, even though power indications were unchanged at 25x2500
* Those events were consistent with carb ice, for which conditions were excellent
* During a post-event runup on the ground, the ignition system checked fine, but the next day one p-mag was completely dead
* And the propeller response during next day runup showed a sluggish return to normal operating RPM

One more detail that should not make a difference -- about eight hours ago, the oil was changed from Aeroshell 100W to 15W50.

The prop is a HC-C2YL-1BF/F7663-4, shipped 8/03, dynamically balanced June 2013 with no changes made. I found no record of the prop having gone to the shop otherwise.

Prop governor is an MT P-420-3, and similarly appears not to have been off the airplane since original installation.

So back out to the airport tomorrow to do more checking, things that I didn't do today because of premature celebration of having found a hard failure in the ignition. And since one mag is going to the shop anyway, he suggested sending both in.

I wish it was in its own hangar 15 minutes away instead of being 50 minutes away...
 
Ed,

If you haven't already sent the mags back, I could loan you one to get your baby home.
 
I would say that no loss of MP is not consistent with carb ice.
You talk about ground speeds, but winds can change. Did you see a loss of indicated irspeed?
The prop runs on oil. Have you checked oil level?
Another possible explanation for the sluggish prop: the recent change in oil type may have moved sludge to the crankshaft and prop hub. If you pull the prop you may be surprised at how much gunk there is in there.
 
More details

Thanks, Bob.

Don't think wind was a factor.

Checked the oil before first takeoff.

Pulling the prop seems feasible if I can find a helper.

Thanks
 
Glad you are safe. If it was water I would think that instead of surge it would run rough or quit. Good reminder to always have a plan in the back of your mind. Please write another note when you discover the problem.
 
HT wires?

Congrats on making a safe landing. Maybe I missed it but while you have your cowl off, I would consider checking the continuity and resistance in all of your HT. Sometimes these can go 'south' alarmingly fast. We are all looking to to see what the eventual remedy is - hope that it is simple and not too much$$$. Best to you.
 
Loss of power

P-Mags with all the latest revisions caused a significant loss of power in my engine on three different occasions, two of them resulted in emergency landings, and on each occasion the mags were sent back to the factory for rebuilding. On each occasion I did a mag check, turned off the misfiring PMag, and landed with the good mag. My problem typically started with momentary small drops in rpm and power and then quickly progressed to severe misfiring. The mags ran fine during the mag check but problems started after climbing to about 4000 ft. When this severe misfiring occurs, a mag check is required to quickly turn off the misfiring mag, otherwise this continued pre-ignition will quickly destroy your engine. In my three instances the problem mag was firing in a dangerously advanced position causing severe engine detonation and immediate power loss. I also noticed after the first scare, that the oil temp quickly spiked from 180 to 245 degrees and oil pressure dropped 20 psi. My first thought was that the engine had run out of oil, which wasn't the case at all.

Brad at Emag mentioned that the three failures were caused by worn out bearings that required replacement plus one circuit board was replaced the last time. When the bearings get sloppy the magnet on the tip of the main shaft moves too far out of alignment causing the encoder to misjudge TDC and misfire. Each time Brad was very accommodating and provided good customer service. Brad mentioned that bearings rarely require replacement and it may have something to do with the gear harmonics in my particular O-235 transfer case. I notice that Emag now recommends checking the bearing side and end play at regular intervals.
 
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I'm thinking intermittent Pmag failure, which would cause same sensation AND the prop would surge due to rapid power changes with the one mag coming on and off. Essentially you'd have two things (mag & prop governor) yanking the engine power around.
 
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