Rocket Glider.....

Or, "Looking in the mirror at a Bonehead" Part Two, The Rest of the story...

It is with some trepidation that I write this, but if we can stand peer review then we probably should hang up our headsets.... This is a long story, but i will try to do the short version..... So here it is....

In light of the Mirror story, I wanted to get some time on the Rocket in anticipation of a trip that would have taken me from Iowa to West TX then CenTex, then home, this weekend. So Wednesday evening I took off to do some flying.

I also needed to do some acro to get warmed up for the summer show season.... I was about 15 miles from the airport at an area over a farm strip where I sometimes practice. I like to practice over or near a runway.... I made a low pass to inspect the condition of the runway after the recent snow melt and to notify the farmer that I was in the area. He likes to watch...

As I was pulling up off the low pass, I started adding power and the engine stumbled. It was running, but not right. It would not accept throttle without dying. Pulling the power back smoothed it out. I did all the standard stuff, switched tanks, boost pump on, mags, fooled with the mixture, but the fuel flow was about 6 gallons per hour and nothing changed that. I could climb at that fuel flow so I climbed higher over the strip and pondered my options... I was somewhat concerned that the strip might be soft, and I wanted to get home, but it was a long 15 miles to the airport so I landed. The farmer came out and we pulled the line from the fuel servo, turned on the boost pumps and both tanks ran a full stream of fuel.... I pulled the finger screen out of the servo and it appeared perfectly clean....

I hooked the line back up, fired up the airplane and it ran fine.... Now what??? I called my Mechanic and we chatted for a while.... We talked about unporting a fuel tank because of a hung up flop tube... Maybe it was airlocked.... (I did not buy that) I decided that I would run it some more and if it made power for a significant period of time, I would launch and fly home over a 4 lane divided highway that went directly to the airport without much traffic at all.

Rightly or wrongly, I took off. Even when it was acting up, it would make enough power to maintain flight, so I took off and it ran perfectly. I climbed way up high and it purred all the way home... On the way I decided I would try to duplicate the event, so over the airport, Left tank, low power, steep descent at high speed.

After about a 3000 ft descent I added power, and again, it stumbled and again, it would not take power.... Again, I tried everything I could think of, but nothing made a difference. I took the opportunity to practice a deadstick landing. I pulled the power back, hit the high key, bent it around and landed exactly on the fixed distance marker and taxied in... I let the airplane sit for a bit, went out fired it up and it ran perfectly..... Hmmm??? I went home and I called another mechanic,

This mechanic said it was possible to ice up the Venturi in an injector servo and that will shut off the air signal in the servo diaphagm and it will only deliver the idle circuit fuel.... The next morning I called Don Rivera at Air Flow Performance. He was perplexed. He said it could be ice, but he doubted it. He did say if it was ice it could do what I described. He wanted me pull it off and send it in,.... I don't like sending things in when I don't know whats wrong with them, especially when it could be something else.... I like to find the problem so that I can know I have fixed it.

The ice was the best explaination I had heard so far. The evening before it was cold and high humidity. This made sense as to why it would run after being shut off.

The next morning a high pressure had come thru and cleaned up the humidity. I looked everything over again, buttoned it up, fired it up, went to the long runway and took off...

Now before anyone says I am totally crazy, The way our airport is laid out, there is no time on a 18 departure in the Rocket where I dont have a good option.

I climbed up to 8000 ft over the airport, it ran great. I tried several low power, steep descents for nearly half an hour. It ran perfectly..... "It must have been the ice"

As sure as I was that it was ice, it was with some trepidation I loaded up my stuff and headed for Texas.

I have several airport options after departure. It was severe clear all the way to TX, so I filed for 16,000 feet and away I went. At 16,000 there is no place between MCW and my fuel stop in Wichita where I did not have an airport within gliding range.

It was running great and I was pretty well convinced that ice was the culprit, until about 15,500. The EGTs started climbing and got rough. I told ATC that i wanted to return home. Again i tried everything, but the fuel flow kept slowly dropping and I realized that getting back to Mason City would be tight. By then I was almost directly over Belmond. I had 3 or 4 airports within range at that point, but i chose the one below me.

I told ATC that I would cancel and land. They asked me relay through another airplane to them when I safely on the ground.

It is a long trip from 16,000 to the surface. I had lots of time to kill so I tried everything to identify the problem... No luck... it would not deliver more fuel. The fuel flow was below 3 gallons and really could barely tell the difference between the mixture forward or idle cut-off. I pulled the prop back and spiraled down over the airport.

The actual landing was a non-event. I was over the high key at 1800 AGL, did my 360 and when i had the airport made, pushed the prop up, dumped the flaps and slipped like a big dog to a landing just past my aim point on the runway.

The engine was idling, but advancing the throttle at all would kill it. I radioed to an over-flying airplane to tell center that I was safely on the ground....

It would not taxi in the grass. I pulled the mixture, it quit, I pushed the throttle up and hit the boost pump, the fuel flow went to 8 gph. I hit the starter and it fired up, ran fine and I taxied in....

I was done trying to diagnose the problem.... The servo is on the way to Air Flow Performance. I have pulled all the hoses in the fuel system. They all look good, but I will replace them because it's time. I still have no idea why it would not run...

Some will disagree with my descision to fly it to diagnose the problem. I can accept that. I can argue that after the first take-off from the farm strip, I was never in a place where I did not have a good landing option. I can argue that at that point I believed, even when it was not working, it would deliver enough fuel to fly. Still it would be pretty easy to argue that I should not have taken off from the farm strip. That is a fair criticism...

As for what is causing the problem? I am totally stumped. I hope Don finds something, or the next take-off will be no fun at all....

It may end up being connected with the painting (I hope) because the airplane was dormant or the dust in a paint shop.

If paint dust proves to be the culprit, that is pretty scary.... It could have been several more hours before the problem arose.

There is room to discuss whether I should have tried to find the problem by flying, but what this really highlights is how stupid it was to fly it home from the paint shop and land in low IMC. That flight was the flight before this problem surfaced. Had the engine started losing fuel flow in Low IMC it could have been a very different outcome.

No matter what altitude, a dead stick to a 2-300 foot ceiling is a bad deal. Even if you are directly over an airport.

I will file a report when (& if) I figure out what the problem is.....

My guess is you have some junk in the flow divider, or your mechanical pump is going bad.

Wow...things that make me go "Hmmmm....". Perhaps the ole'84 just ain't comfortable in her new clothes yet!

Good to hear it all worked out though.

Cheers,
Stein

Interesting....

Thank you very much for posting the report. I found something similar in the "perplexing file" A Beaver on floats, if I remember correctly, would have engine out events and nobody could figure it out. It would run correctly after landing and it was a real pain. The culprit turned out to be a small piece of wood in the fuel line that would change orientation every once in a while and cause the engine not to run correctly. I wish you the very best of luck in finding the culprit. Please keep us informed.

Best
Brian Wallis

By any chance is there any tape covering your tank vent???

Had the engine started losing fuel flow in Low IMC it could have been a very different outcome.

Click to expand...

A scary "if" thought for sure. However, at this point in the diagnosis process there is no evidence to show paint shop work and low fuel flow are related. Premature to beat yourself up without a connection.

Mike S said:

By any chance is there any tape covering your tank vent???

Click to expand...

Mike I thought that too. Blocked vent, water in vent freezing etc, but a switching tank should cure the problem if only for a few minutes.

There has to be a clue in the pass/pull somewhere.

?, I have not done the math, how long a flight was the flight after paint? Just trying to determine how long it has run fine on both tanks since paint. Paint is the one change we are aware recently that may provide a clue.

rocketbob said:

My guess is you have some junk in the flow divider, or your mechanical pump is going bad.

Click to expand...

I have a Matronics FF so I have to push buttons to get fuel pressure, and that is one thing I forgot to check. The unit was not alarming so it must have been making pressure and shouldn't the electric pump fix that?

Some one told me that the flow divider screen is the tightest screen in the system. I did not take the divider apart, I just shipped it off. The servo is 10years old and has 1000 hours on it, so it won't hurt to have it looked at....

Tailwinds,
Doug Rozendaal

I had an intermittent rough running IO-360 after overhaul. Take off ok, but rough engine sometimes at full throttle during climbs. Problem turned out to be a pollen grain in a fuel injector. Worked like a ball valve, plugging the injector a higher fuel flow.

I think Kahuna might be on to something with water somewhere in a vent line. There was probably rinsing involved with the paint job.

Climbs are ok because the ambient pressure is decreasing, perhaps at a similar rate to the pressure drop in the fuel tank due to fuel consumption. During a descent, the pump has to work harder to pump fuel from the low pressure tank to the higher ambient pressure.

I would bet against the fuel servo or flow dividers or induction ice. The drop in fuel flows is too extreme.

Blow air into the tanks carefully, and watch the vent lines to see if anything is puked out. The vent lines take a tortuous path by design, and could certainly trap some water.

It is really interesting to me this came up, after your bh part 1 thread i was wondering what was the worry, or rather what takes a couple hours to manifest itself after a disassemble & paint instead of being fairly obvious within the first 1/2 hour of flight. glad you are ok and hope you track it down.

I am with the vent line scenario. If something about the painting affected one tank's vent line then there is a good chance that the second tank got the same pre paint treatment. Remove the lower tank/fuselage faring and remove the coiled tank vent lines. As suggested blow them out, but also consider making a new set, they are just tubing. It is possible that some solvent got in the vent system and that mixed with some dust has created a gummy mess. You can also reach in the filler cap and feel for the end of the vent line. You might be able to slip a bit of tubing over the end so that you could put some pressure on the segment of line that goes through the tank.
I am not sure which filter system Mark had on that plane but I would most certainly inspect and relace them.

AlexPeterson said:

I think Kahuna might be on to something with water somewhere in a vent line. There was probably rinsing involved with the paint job.

Click to expand...

Alex,

It is not the vents, first off, when I filled it with fuel, it puked some gas out of one of them before I took off... Also on the last flight, I never descended. Further, if it was vents, changing tanks would solve the problem, even if only for a few minutes...

Doug

Did you check the fuel at the airport. I'm assuming you got gas from the same truck at the same airport before both flights? It sounds more like a flow problem but it never hurts to check the simple things.

B25Flyer said:

I have a Matronics FF so I have to push buttons to get fuel pressure, and that is one thing I forgot to check. The unit was not alarming so it must have been making pressure and shouldn't the electric pump fix that?

Some one told me that the flow divider screen is the tightest screen in the system. I did not take the divider apart, I just shipped it off. The servo is 10years old and has 1000 hours on it, so it won't hurt to have it looked at....

Tailwinds,
Doug Rozendaal

Click to expand...

There's no screen in the flow divider. The fit of the piston in the divider is tight, 0.0004" (four ten-thousandths) IIRC. A tiny, and I mean tiny, piece of junk that can easily get thru the main filter and the screen at the servo and hang the piston up. If you had no pressure alarms but couldn't get more than 8 GPH the problem is somewhere firewall-forward. I have seen a fault in the divider cause a forced landing.

As I recall your airplane has a Romec gear-driven fuel pump and those tend to be pretty reliable.

I would also look for any loose connections where your pumps could be sucking in air.

Doesn't sound like (to me) a fuel tank venting issue.

Any chance of some form of vapor lock?

rocketbob said:

There's no screen in the flow divider. .

Click to expand...

Don Rivera says there is a screen in the flow divider... He says it is pressed in.

Tailwinds,
Doug Rozendaal

Hindsight question.

Given that you could climb under the conditions stated and there was a concern about the field below you being soft, why not climb to 14,500' or higher then go to your home field?

My experience with an in-flight problem was the loss of the alternator (failed/broken connector). I did not know how long my systems (including one electronic ignition) would last, and my expected arrival at my desired airport was approaching sunset. So I landed at an airport nearby to diagnose and fix the problem. I still don't know if I could have made it to my original destination on battery power. I took the known of landing with adequate battery power rather than lose radio and one ignition short of the preferred towered airport outside of Atlanta GA.

I experienced the exact same problem with an injected engine on a T18 Thorpe that I was test flying after a lot of work had been done it. It turns out that the spring in the bypass valve and ball were rusty and every once in a while it would stick open not allowing full fuel flow to the engine. Low power settings no problem above much more then 1/3 throttle and the engine would stutter.

Flow

B25

I have had the same problem. I think you will find the filter at the inlet to the servo partially blocked with very fine material. When you pull high fuel flow, it pulls the particles up tight against the filter media. When you shut it off, it falls back and flow is restored.

Interestingly enough, if you pull the mixture to full cutoff a few times it may clear long enough to restore.

My particles were brush or commutator material from a degenerating electric fuel pump. Try blowing through it before you clean and again afterwards. i cleaned mine on a white paper towel with carb cleaner. Amazing how much powder was in there.

B25Flyer said:

Don Rivera says there is a screen in the flow divider... He says it is pressed in.

Tailwinds,
Doug Rozendaal

Click to expand...

Didn't realize it wasn't a Bendix divider, those don't have the screens.

A complete long shot

Check all of your solid aluminum fuel lines for cracks. Really doesn't match the symptoms, I know, but why not, while you're looking for *something*. I had a cracked line in my old RV-4 forward of the firewall and, to make a long story very short, wound up with the aux pump pumping a gallon a minute overboard in the engine compartment...

From that and other experiences, my philosophy on experimentals was "every flight is a test flight." It's scary how many folks build an experimental, fill it with all kinds of cockpit gadgetry, and then expect it to not only never have problems, but also to compensate for any pilot shortcomings...

Ed Wischmeyer
AirCam and pristine Cessna straight-tail, looking to sell both and get an RV-8 or maybe an F-1

I had exactly the same symptoms about a year after I started flying my F1. Fuel flow was down to about 5gph and fuel pressures were elevated. Problem would come and go. Blamed it on icing which with the AFP setup was highly improbable. Did everything you have done except everytime it occured I checked the throttle body inlet screen. On the last occasion it was clogged with something viscous and slimy.

Turned out to be fuel contaminent. Cleaned the tanks and entire fuel system and no more problems.

First of all, I think you are to be commended for sharing your story with us. It does take a bit of courage to face possible critique for "boneheaded" moves. I don't think there's a pilot out there that hasn't had some errors in judgement. The important thing here is to learn from them, and share your story with others. Hopefully we can all learn from such events.

I remember flying home from Sun-n-Fun some years ago in my VFR C-172 with my 5 year old son with me. It was great flying weather all the way...until the last 100 miles. I was coming up on an approaching cold front with rain showers, and the visibility very slowly began to deteriorate with light rain. Very smooth, but becoming marginal VFR at best. I knew my landmarks at that point in the flight, and I had my trusty LORAN working. I was working my way around the DCA Class B airspace ( prior to 9/11) and knew where I was going. Probably 30 miles from home, at one point the visiblity was down to a mile or two from 1500'. I remember thinking to myself that this was probably not the smartest idea.

It was then that I glanced over at my sleeping 5 year old son, and thought just how stupid this was. I flew on out of the rain and landed at my destination and got the airplane back into the hangar before the rain arrived.
And it rained for a whole 20 minutes... sunshine behind it. I should've known better, because I am a professional pilot. I put my kid at risk by scud running when I really didn't have to! Very stupid indeed. I've never forgotten that, and hope that it is just one more little tidbit to add to my experience file...and hopefully make me a safer pilot.

I won't go there with you on your decision to fly after the paint job. You've already beaten yourself up enough on that. As far as the mystery gremlins running amuck in your fuel system, it sounds like you took all the safety precautions possible when trying to "fly/diagnose" your problems. You seem very safety minded when dealing with this, and not taking unnecessary risks while working with the problem. Thus far, you have been "cheating at cards" by always having an Ace up your sleeve when you fly. As well you should. As well we all should!

Good luck with getting this issue resolved. This forum is a great resource as we all know. Many ideas flowing about possible cause and effect. And most of all thanks again with sharing your story.

Jeff,

You are too kind...

Tailwinds
Doug

Troubleshooting alternatives?

Please forgive the thread drift, but with an intermittent problem like this (or the others which have been mentioned), what options are there for troubleshooting other than actually flying the aircraft? How is this sort of problem resolved in the certified world?

Some really good replies here

Contamination seems to be the leading probable cause.

This is not a criticism just a difference of choice. I would not have landed in the farmer's landing strip when the original symptoms occurred. As long as I could sustain steady state power with no faltering indications I would have flown the 15 miles to the home airport at reduced power.

Bob Axsom

mcencula said:

Please forgive the thread drift, but with an intermittent problem like this (or the others which have been mentioned), what options are there for troubleshooting other than actually flying the aircraft? How is this sort of problem resolved in the certified world?

Click to expand...

I really don't have a clue what the problem is with Doug's particular plane (and am anxious to hear the results), but even in the certified world, sometimes you just have to go go flying to figure it out. The important thing is that if you take the machine aloft, you need to have a backup plan if the results don't turnout like you hoped. In this case, once trouble had presented itself, I think Doug provided himself backups at each step, making decisions that always left him an out. That's good planning.

It is no sin to take a risk, so long as it is calculated and you leave yourself an "out". The trick is making sure tat you are honest with yourself that you have taken into account the big risks, and that your backups are realistic.

Heck, even "Click and Clack" (the Tappet Brothers) talk about strapping a mechanic to the hood of a car and taking it around the block to listen for weird noises.....

Paul

As for troubleshooting on the ground vs. flying, I'm with Paul. Sometimes it just won't fail on the ground. I flew a T-34 once that quit about the time I made a power reduction after climbout. Power went right to idle, and of course I switched the fuel selector, and shoved power levels all forward, and checked the mags. It immediatly went to full power again. At the same time I was given a frequency change to departure. Right about the time I started to make the call to departure, it quit again. I flipped the fuel selector back (might as well do something, right?), and by the time I finished my call (now stating that I needed to go back), it caught again. It must have quit 3-4 more times, before it settled down with a power reduction and ran continuously. I landed safely right from where I took off. I tried to duplicate it on the ground to no avail. But feeling much safer on the ground than I did in the air just a few minutes ago, I called the club mechanic who came out and "verified" there was nothing wrong with it. He, too, did really long full-power ground run-ups. Told me to go fly it. Of course, I said, "you go fly it first", which he did. He came back white as a ghost. Told me it kept quitting. I said "told you so." . Now it gets even better. After checking "everything" they decided the engine was close enough to TBO that it needed just that, so it was sent out for an overhaul. Came back about a month later, he reinstalled it, went flying, came back white as a ghost again. Now, replaced fuel system in the aircraft. Same problem!
Time to back off and look at what hadn't been changed. Air flilter? Yep. Turns out the air filter was collapsing at full power in the air only. That was a very expensive lesson. Luckily, no one got hurt in the meantime. I never forgot that experience.



Vic

Testing Fuel flow

After having B25s problem, in the air, twice, over mountains, I added a checklist item. After cycling the prop, I quickly set full rich and dial in about 21 inches at 2500 rpm and note fuel flow response. Just takes a few seconds. After a while, the proper response, that is rate of change and max rate, has become very apparent as have malfunctions (all slowly plugging filters so far).

If you have a good fuel flow instrument, use it on the ground as well as in the air!

I agree though that some gremlins only awake once in the air!

zav6a said:

I agree though that some gremlins only awake once in the air!

Click to expand...

Makes me ponder what changes occur while in the air------big ones seems to be angle of attack, and vibration level.

Both of these would aggravate a fuel contamination issue ----crud in the tanks???

But then, a Rocket has the little wheel in the correct location, so it is already sitting with the tank in climb attitude while in the ground.

Will be interesting to find out what the problem turns out to be, a chance for a lot of us to learn.

I talked to Don Rivera yesterday... He says there is nothing wrong with the Servo.... He said the divider was functioning normally, but had some wear... He is rebuilding that and I should have it back tomorrow...... Then I guess I put it together and go flying again.... The good news is, I have never had a problem at high power..... Which is the thing that makes it most difficult to diagnose.....

Tailwinds,
Doug Rozendaal

PS, Anybody going to be at Maxwell AFB this weekend? I will be there flying the Red Tail P-51. Stop by and say hi...

Fuel system description?

Check valves were mentioned in an earlier thread. If you are so inclined Doug, a detailed description of the fuel system would be helpful. The next "fuel limiting event" could be zero fuel flow... Seems like one event was about 6 gph, another 3 gph.

Is it ok if I reprint this?

Vic,

I edit the newsletter for my chapter (32 in St. Louis), and if you don't mind I'd like to publish your experience in an upcoming issue.

Jim Bower

Troubleshooting 101.

There are three things that make the engine go, FUEL, AIR and FIRE. This problem is with one of these. That narrows it a little (hey it's not radio noise, so that's good news).

Everything definitely points toward a fuel delivery problem. You have checked the obvious. You said that fuel came out of your vent lines? I am not familiar with your vents, but if that's the case there could be a low spot in your vent line where trapped fuel is blocking the air? That would only affect one tank, however if you have identical lines in the LH and RH, it is possible that you have twin failures. I've seen stranger things.

Sure, Jim.

Vic

Here's a thought - you've got the AFP injector with a recent "thumbs-up" from Don himself that it's all happy and working. If you can go flying and get the problem to surface again (in an appropriate place of course, with a good altitude cushion), hit the purge valve on the injection. This will dump all the fuel from the divider directly back to the tanks, holding that for 3-4 seconds should replace any heat-soaked fuel in the lines and may shed some light on a possible vapor-lock scenario, and you should see your fuel flow go high with the valve open if you don't have a blockage in your lines somewhere. Keep your airspeed up so the prop windmills during the zero-power time you've got the purge valve activated, and be prepared for no power return in the case that may aggravate the situation. Either way, you'll learn something.

Similar Problem

I had a very similar issue. ECI IO360- Bendix Precision FI system. Rough running. Determined #1 cylinder wasn't firing correctly. Local A&P assisted in investigation.

Problem- small sliver of rubbery material blocking "both" the port from the spider and at the actual injector. Cleaned out, other ports checked, measured fuel flow test completed.

Also checked the AFP fuel filter, again. (Had just done that the previous month on the Cond insp.) Checked screen in FI servo. Nothing in either one. Tank sumps clean.

All hoses are Precision Hose Technologies. No previous problems.

In summary, it is amazing how little it takes to cause a problem

The Rocket is home!

I got the Fuel Servo and divder and spider back from Air Flow Performance today. He said the servo was fine, the spider had some wear and a minor leak... He did not believe that it was causing the problem I am having....

I rebuilt and replaced all the lines foward of the firewall. I put it back together, fired it up, it ran great.... I had surveyed the roads and fields around the airport and knew where I was going depending on where it might quit. I took off climbed up over the airport. It ran great, I hung out for a bit. It is 22nm from Belmond to MCW and once I had gliding distance to one or both of the airports...

It ran great.. No issues, I flew back to MCW. I flew over the airport doing everything i could think of to Pi$$ it off for quite a while. No luck, everything worked fine. So I came down landed... Just to keep a good string of power off landings going, I hit the high key, pulled the Mixture and dead sticked it to the fixed distance markers. I landed about 30 ft past the paint....

I am at a total loss... My plan is to stick pretty close to home for a while before I blast off on any long trips and I will be flying pretty high for a while... No mountains, no trees.....

Still scratching my head...

Tailwinds,
Doug Rozendaal

Simple things

Hey Doug
Does your system have a sniffle valve in the bottom of the elbow downstream of the servo? Maybe it is sticking open somehow sucking air and tricking the servo.
Also I have flown my Rocket home twice now with known problems, to self diagnose, and also just because I wanted to work on it at home instead of a field somewhere. All sounds reasonable to me. Just my opinion.
Kevin Shannon
two RVs and a HRII
(kept the HRII)

???

"Hit the 'high' key???"

Curious,

pierre smith said:

"Hit the 'high' key???"

Curious,

Click to expand...

You know how the "Key Position" is generally taught to be a point somewhere on downwind abeam your touchdown spot (from which, you can make the runway without power if you fly a tight pattern)? Well, a "High Key" is when you have a glide ratio of a brick and you need to be a little higher than normal to make the runway without power. For instance, the "High Key" point for the Shuttle approach is about FL400.......

K Shannon said:

Hey Doug
Does your system have a sniffle valve in the bottom of the elbow downstream of the servo? Maybe it is sticking open somehow sucking air and tricking the servo.
Also I have flown my Rocket home twice now with known problems, to self diagnose, and also just because I wanted to work on it at home instead of a field somewhere. All sounds reasonable to me. Just my opinion.
Kevin Shannon
two RVs and a HRII
(kept the HRII)

Click to expand...

A stuck sniffle valve or a large leak will prevent the engine from idling below a certain point but they usually will run fine at high power.

Sounds like the flow divider was the culprit.

The High Key is a target. As Paul suggested the Key, or Low key is the desired altitude abeam the touchdown point. On a Simulated Flameout Approach, SFO, or Deadstick Overhead it is the desired Altitude over the point of intended landing. In the Rocket I like 1800 AGL. 1500 will work but it is a pretty tight pattern.

So when the engine quits at 16,000 feet you spiral down to hit that point at that altitude and all your worries are gone. Now you are doing a known maneuver with a known outcome. That lowers stress and that improves pilot performance.

Everyone should know these numbers for your airplane, because if you think engines don't quit, you're not thinking....

Attached is the diagram out of a T-28 Manual.....

Tailwinds,
Doug Rozendaal

Thanks much, Doug...

...would you hazard a guess as to the altitude required for a -10? I'm gonna find out, but it appears to be essentially an overhead approach with no power.

Best,

pierre smith said:

...would you hazard a guess as to the altitude required for a -10? I'm gonna find out, but it appears to be essentially an overhead approach with no power.

Best,

Click to expand...

This is a great discussion.

Doug, as an IO-540 driver, I've been watching closely to learn of the smoking gun (if it gets ID'd) so as to keep a keen eye out for it! FWIW, sounds like you handled things cautiously and professionally throughout.

Pierre, the analogy of the overhead with no power is a good one. Navy calls this a Precautionary Emergency Landing, or PEL (at least in my day ). When we did them in training, we called it a PPEL (Practice PEL). Could be done power off or with power set at a specific value (as we did with low/no oil pressure in an A-4). Each airplane had its own profile, but the high key, low key concept was common. The profile could also be "unwound", if you will, to make a straight in profile (not quite a space shuttle approach, but steep).

This is a good nudge to go out and explore where high and low key is in the Super Six, as it has the same wing as the Rockets, and comes down like a fridge with wings, power off (sort of, not that bad, but something to plan around). 1800' sounds like a good starting point Doug. Pierre, it may not be a bad starting place for a 10 either, and you can work it down as you play with the glide, and with the angle of bank that works to keep it comfortable, yet close to the field. Might be a slightly different altitude between you solo and with 3 pax, and if there is a lot of wind, add some spare altitude, or keep it closer in. In the end its a matter of making the field without having to wrap it up too radically in the turn.

Will be a good exercise. Doug, glad the Rocket is flying well now, and still hoping to see you nail the culprit!

Cheers,
Bob

Yeah, it's a great discussion!

...and taught me a valuable trick that I'm gonna practise....who'da thunk? Makes me wonder how many other really good 'Tips' like these are out there that should really be shared.

Best,

To be clear, I did not invent any of this stuff, I have just hung around some really sharp pilots. Being not so smart, I have to steal good ideas where ever I can....

Pierre, Here is how to find the High Key. Go up to about 5000 AGL over your airport slow to Best Glide speed. Fly up the centerline of the runway and at midfield pull the mixture or turn off the mags. Then do a 360 40-45 degree bank turn. Note your altitude at the 180 point (the low key) loss and then add about 300 feet to both numbers for a short final and suboptimal pilot skill. Do this with the prop forward, because you high key needs to be worst case scenario and if oil pressure is not available you wont be able to "feather" the prop.

Then go back up to that altitude and do the same thing with the power at idle and one notch of flaps. The altitude loss will be similar. If not find a flap setting that simulates a dead engine. Then using that configuration go down to the high key and practice over the runway to a landing. I use the fixed distance marks as the fence and the objective is to touch down on them without going short. Slow but not 3pt. The objective is to spot land without going short, and get on the binders. Going short and hitting the ditch is 100% fatal. Being a touch fast and hitting the fence at 20 mph is 100% survivable.

Learn to regulate the radius of turn, the addition of flaps and the speed to consistently hit the spot. This is not difficult at all, but it requires practice. I practice this all the time. Idle landings to the fixed distance markers from abeam the touchdown point (the low key). Find out what happens when you get a little wide or a little slow. The whole thing falls apart so fast it is a real eye-opener. Done correctly it is easy. But once you lose it, your only choice is to pick a closer landing spot, because if you get below the profile you have very little time to correct it.

The real objective is two fold. One is to learn the ability to sense the energy state of the airplane relative to a spot on the ground. The other is the ability to see a line in space that takes you from where you are to where you want to be and then be able to fly that line.

These are not textbook skills. These are the finer points, or the art of flying. For those who are challenged like me it is not an easy skill to learn. I've been at it for 33 years and it Pi$$es me off when I fly with some low time kid who has the touch and can do effortlessly..... I am not that person, it was years of beating my head against the concrete to gain the few skills that I have.

Tailwinds,
Doug

Hi-Key Lo-Key

Doug,

Thank you for your explanation of how to determine High Key and Low Key for a given aircraft. My primary flight instructor taught me the technique and I practice it regularly. We're all taught to "fly the plane", but the outcome of an engine out or similar event is certainly more predictable when you have plan that has been regularly practiced. Flying a Cub at my home field, it's not uncommon for a group of us to challenge each other to prop stopped dead sticks to an exact stopping point on the runway. The winner is generally determined by inches.

To those who have not already determined Hi and Lo Key for your aircraft, DO IT NOW and practice it regularly! Challenge yourself... instead of doing a TnG, have fun practicing the 'Keys'!

BTW: Those youngsters sometimes pi*s me off too... what takes me ten or more attempts, they do on their first! What's worse, they're also smarter than me!

Great post... Great info... May save a life!

Have a Great Day!

The other beauty to the Hi Key / Lo Key engine out pattern (or the PEL as taught in the Navy) is that it establishes a known set of check points that, if you can intercept them at any point, it assures that you can make your field. In other words, if you do not have enough altitude to glide to hi key, you can set up to intercept the pattern at some point below hi key - like maybe a glide into lo key abeam the intended point of landing. At that point, you now know you can make the field by flying through the remainder of the checkpoints.

It beats the **** out of trying to judge a glide into a field from straight in at three miles out. You don't really know if you'll make it until you do - or dont or overshoot.

Once you hit a know spot in the pattern, as Doug said, you are home free. The pressure is off. Fly the remainder of the pattern well (as you have practiced), and you will make the field.

For my constant speed -6, I use 1800 agl Hi key, 900 feet lo key, 25 degrees AOB. Flaps down when the field is made. I practice with throttle at idle and a notch of flaps that just matches the decent rate of a dead engine (again determined by practicing engine out glides.

The pattern can be tightened if a little low, extended if a little high, slipped or flaps held to make adjustments. You are making the adjustments intelligently in reference to known points - not guessing based on eyeball judgement.

This is a bit of thread drift but this is a very valuable technique that I am not sure is taught routinely in the GA world.

Maybe should be a new thread in the safety forum.

That was great seeing the old T-28 manual again!

Good luck with the trouble shooting Doug.