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RV-3 Flight Number Two?.There is a Reason We Prepare!

Ironflight

VAF Moderator / Line Boy
Mentor
So RV-3 flight number one ended as planned on the wide runway at our neighboring airport. With a recent cold front passage, the winds were gusty and building, so we activated our contingency plan, tied the airplane down, and head home in our ground vehicles. The forecast was for the winds to drop as the day went by, so we re-planned for a 1500 (lcl) gathering time, and sent the team home for a few hours. When we got back together, the weather was great, so we launched for the flight we had planned – basically, a twenty-mile long “race track” for engine break-in. All went well until I had to make this call…

“OK, I've just lost power – going for a good glide speed.” Test Director Steve, riding in the right seat of the chase plane, responded in a calm voice “Copy that, lost power – I’ll listen, you talk.” No hint of panic in either voice, but then, you have to understand, Steve and I have worked together, often sitting side by side in missions and training, for close to 15 years. We have handled THOUSANDS of simulated emergencies and failures – along with a few real ones. We know how each other thinks – and we were prepared. I calmly worked through the standard power loss checklist – the Whirlwind kept going round and round, but I had no throttle response. I switched tanks several times, tried the boost pump, played with the throttle and mixture – no joy.

“OK chase, I’m descending through 3,000, and nothing’s working, I’ll keep trying – see if we can make the Creasy strip (private field of a co-worker).” While Steve was checking the GPS, I already realized this was too far to reach. We were going to have to find a place to set down off-airport.

OK, so hold that thought. This was not the first time this scenario had run through our mind. In fact, we were over my regular practice area – A spot I know upside down as well as I do right side up. There was a reason we were here – miles and miles of cultivated fields, criss-crossed by oil-field roads. The east-west highway is often sparsely-traveled, and there are few power lines. It also wasn’t an accident that we had a chase plane. No, they weren’t there to play Yeager games – they were there to communicate, keep me on plan, and keep my location in sight – in the air – or (as now appeared likely) on the ground. We were about fifteen miles from home base, and ground radios just don’t reach that far. Speaking of ground radios, our ground team was on standby for just such an event. After helping make sure that I launched with my checklist complete, they had gathered up the extinguishers and other standby gear and headed back to our home field – with radios and cell phones ( with GPS) in hand. The mission was thoroughly briefed – right down to who would do what in the event of an off-airport landing. No one really thought we’d be there – but preparation and years of training are hard to beat.

“OK Steve, I’m through 1500’ – we’re going to have to put down. I’ve got a gravel road running north-south, intersecting the highway, a mile west of the big antenna. I’m in good position with plenty of energy – I’ll land to the south.” Truth be told, these oil field roads are better than a lot of gravel runways I’ve seen. And frankly, it was wider and more open than our home airpark strip – longer too! I picked my spot to allow plenty of room for an under- or over-shoot, and dropped the flaps. This would be my second landing in the RV-3…but it seemed to fly just like an RV, so I figured I’d fly it like one. As I rounded out in the flare, Steve called that they had me in sight – I called that I was down and safe, totally undamaged, and would get on the cell phone to the ground guys. I kept the radios up as Louise and Steve circled overhead and I pulled off my helmet to use the phone. Oh yeah – we had the cell phone numbers of everyone on our team right on the briefing card. The ground crew was surprised, but calm, and I gave them the GPS coordinates off the G3X before shutting it down to save the battery. Then I realized I had Google Maps on my Iphone as well….and cell towers everywhere. I put my helmet back on and told Steve the cavalry was coming, that Chase was released, and they should call when they were down to see what the next need was.

To shorten this long story, it was too close to sunset to make an effective effort at fixing anything that evening, and Steve (Test Director) quickly vetoed any thought of further flight that day – citing my own preflight plan that said we’d take our time and be methodical. Besides – no night flying in Phase 1! I had about a forty minute wait for the ground team to arrive, and before it got dark, I had already figured out what had brought us down – at least I was pretty sure of it. But the darkness and caution made the prudent move to tie things down for the night and come back in the morning. The cars on the highway passed by without slowing, blissfully unaware of the airplane sitting a quarter mile up the side road. When the team arrived with tie-downs and covers, we closed “Junior” up for the night, and were happy he was safely out of sight behind a HEAVILY locked oil-field gate. We figured we’d be out of there first thing on Sunday morning, and figured no one would be by in that time – and we were right.

_DSC2761.JPG


This morning, we showed up at the crack of dawn, and easily got Junior going. No damage at all – no dents, no chips, no rocks in the wheel pants. We had spent a couple of hours overnight talking through the most probable cause I had figured out, and the ramifications for further flight. All agreed that it was safe to fly him out (and by ALL, I mean some pretty experienced flight test safety guys), so that’s what I did. Beautiful morning – but we scampered right home for further inspection and testing.

_DSC2799.JPG


OK, so here are a few key points from the story. First, preparation. Second, preparation. Third….MORE preparation. We didn’t take anything for granted, and when we had a problem, we were ready to handle it in as routine a matter as possible. Test flight routine – take it seriously, and plan for all reasonable eventualities. Lots of folks just kick the tires and light the fire. They are referred to as daredevils. The flight test folks I have known and worked with? We can be pretty boring. Pedantic. We do briefings.
_DSC2592.JPG


We think about putting the pilot’s jacket in the baggage area because it can get pretty chilly out there on a lonely gravel road….and we carry cell phones and radios to make it less lonely. And the next morning, we have all the people and airplanes still around to fly again.

Oh yeah, Junior flew three times today – once to get home, then (after thorough examination of the cause) twice more to continue engine break-in and to get some fuel.

The cause of the forced landing? Well, let’s see what you can come up with. It was a single screw backed out about ½ turn. One of those thousands of pieces that go in to making up an RV. We’d like to think that we can catch them all – but nobody is perfect. This was a builder error. Flight test makes allowances for that. I was the builder. We are prepared.

Anyone want to guess about what screw? :eek:
 
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Congratulations on a safe landing in unusual circumstances. My guess is one of the screws that holds the end stops in place on the throttle or mixture.

cheers,
greg
 
Keep guessing

We're tired and will likely score the test in the morning. But, so far you haven't figured it out.

We are curious to hear the possibilities. We tried last night to figure out if there is any other screw on the entire plane that could cause this much havoc when backed out a half turn.
 
Wow!!!

Although I knew something like this can happen to any one and any plane, but I was still seriously surprised it did. Great job planning for EVERYTHING and we its great to hear all involved (including junior) are ok and going strong again!

Best,
 
Either mixture or throttle rod-end would be my guess.

You had an issue, dealt with it, put the plane down w/o making the evening news, fixed it, and flew it safely after that.

Congratulations!

I can't wait to hear what it was so we all may learn.
 
Great Job under pressure!

My guess is the Throttle linkage.

And for the record....pink cowl or not.... You definitely earned your screen name!

Very nice job "Ironflight"!!! :cool:
 
Glad you are OK. Great job on planning and preperation. Geez if it can
happen to you the rest of us should stand up and take notice. Thanks for
telling the story.

Now lets hear the rest of the story.
 
Wow! I always learn so much from every one of your posts, Paul, but this one takes the cake. I'm thankful I get to "steal" so much NASA training from you. Great work!

--
Stephen
 
Great job under pressure Paul!!!

The only single screw I can think of that would cause something like this would be the throttle arm retainer nut, you probably loosened it to adjust the postion of the arm and then forgot to tighten it all the way, when it came loose the engine went to idle power.
 
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Great job under pressure Paul!!!

The only single screw I can think of that would cause something like this would be the throttle arm clamp screw, you probably loosened it to adjust the postion of the arm and then forgot to tighten it all the way, when it came loose the engine went to idle power.

Yep. Has to be something in the throttle linkage. And reading Paul's story, the engine didn't stop, it just lost power - went to idle, presumably.

The fuel selector valve is keyed to the shaft. If the screw comes out (at least on mine) the selector still works fine unless the handle falls into the floorboards. Even if that happened, it wouldn't result in lost power.
 
3 things...

Hey, we can figure this out!

1. Only three things are required to keep engine running:

compression
fuel
spark

2. plane flew out w/o major work, so maybe we can eliminate Compression

3. Loose mag hold down CAN stop an engine, but with one mag still working, there would be a HECK of a noise to let you know you are in grief. Backfire, poping, etc. Also, after an incident like that, I'm not sure you would fly the plane out before a more careful inspection

4. Single point of failure for mags is at the ignition switch. If they field fixed the problem, this is probably out.

4. Two mags makes other electrical grief cause by one screw rare. Mag grounding? nah. I believe your plane does have two mags, right?

5. No mention of cockpit FILLING with gas smell (and they did fly the plane out) means no fuel failure behind the firewall.

So, fuel between firewall and cylinders is probable location.

BUT Louise said linkage was NOT the problem. (did I read that right?)

I can't wait to see the final episode! :)

Dkb
 
awright, yer killin' me! What was it???

(hmmm ... sudden power loss, no oil on belly and no fuel leak. It's not an engine control cable coming loose - even a mixture control would have to back-off two turns or so to come off. Throttle control would never 'come off'. Those are held on with nuts/bolts anyway, not a 'screw'. The problem had to be somewhere in the fuel injection system. Mine's carburated so I can't guess any further)

- Steven
700 hour RV3
 
I have to cast my vote with Walt. If the throttle arm screw backs out, the arm can swing free and cause a loss of throttle control. Because of the critical nature of the throttle and mixture linkages, those screws should be safety wired to prevent such an event.

It's Christmas time! Quit being such a "screw-ge" and tell us what happened!
 
Any chance his IO 320 has an AFP purge valve? Often during installation the safety wire is cut on a couple of screws to mount the purge valve. There have been multiple failures of this where a set screws back out, causing the purve valve to go into by-pass, starving the engine of fuel. Ask me how I know.
 
I'm thinking Kahuna's on the right track. I'm going to venture that 'if' it has a purge valve, the purge control cable attach somehow became loose. Valve went to 'purge' position and things got quiet. To any AFP fans out there, I recommend installing a spring that forces the valve into the 'run' position if this happens.

Glad you had a great team to provide backup, and that your contigency plans were well thought out.
 
?OK, I've just lost power ?


? the Whirlwind kept going round and round, but I had no throttle response.

The above seems to indicate the engine was still running, not merely the prop windmilling.

If that is the case, my guess is throttle arm to throttle shaft screw backed off enough to allow the indexing teeth to disengage.

Other possibility is the quadrant end of the throttle cable, depending on how it is attached to the lever........

Either way, sounds like something between the pistol grip in your hand, and the butterfly in the induction throat.
 
Notes below the quote box...

<snip> ?OK, I've just lost power ? going for a good glide speed.?

<snip> I calmly worked through the standard power loss checklist ? the Whirlwind kept going round and round, but I had no throttle response. I switched tanks several times, tried the boost pump, played with the throttle and mixture ? no joy.

<snip> I had about a forty minute wait for the ground team to arrive, and before it got dark, I had already figured out what had brought us down ? at least I was pretty sure of it.

_DSC2761.JPG


_DSC2592.JPG


<snip> It was a single screw backed out about ? turn.

<snip> Anyone want to guess about what screw? :eek:

Paul, first off, great flying...glad you are AOK. Second, Louise, in the debrief you have that look of a fully-engaged co-test-pilot, but I also see the same look of concern my wife would be giving me if I had just had an off-airport landing...I'm sure you are relieved...and proud of your guy!

I highlighted the notes I think may help solve the mystery above...some more telling than others:

Going for glide speed to me means total or near total power loss...perhaps.

Power loss checklist, not stuck throttle or non-responsive throttle checklist...maybe just semantics, but...

Why switch tanks and switch on the boost pump if the engine is running (versus windmilling)?

Not sure if Paul had tools on the test flight, but he had it figured before the ground crew arrived. Not sure if the pic is that afternoon or the next morning, but the cowl is still on.

I know a purge valve stop failure would shut it down as Kahuna says, but would that happen with the screw out 1/2 turn...dunno...wouldn't rule it out.

I did have a fuel selector come loose once, when my RV was newer-to-me. Switched tanks and a bit later noticed that fuel was still coming out of the same tank as before (that gauge still decreasing). Handle felt a bit loose, but it was still new to me, so rather than try to switch tanks again, and take a chance of it going halfway (to off), I RTB'd quickly. Sure enough, the screw was backed out enough to allow the handle to turn freely, and catch the key if pushed down while turning.

I was lucky...and had the motor quit, I would have been putting the boost on and changing tanks just like Paul.

I'm going with LoopFuz and Pooner this on this one (fuel selector), though Kahuna's sounds very feasible too.

Glad you got the gravel runway landing portion of your Phase I testing done without incident! ;) Whew

Best,
Bob
 
Yep.

Any chance his IO 320 has an AFP purge valve? Often during installation the safety wire is cut on a couple of screws to mount the purge valve. There have been multiple failures of this where a set screws back out, causing the purve valve to go into by-pass, starving the engine of fuel. Ask me how I know.

.....X 2. I bid on a -4 that was totalled following purge valve activation!

Best,
 
Great thread

Well, this has flushed out some great discussion and I'm going to check a few more things the next time the cowl is off. Paul is still asleep and I'll let him do the big reveal, but I can answer a few questions while waiting for my AL mailing tube to depart.

Bob, not surprisingly, your incident analysis is excellent. The plane had loss complete power. Paul made the field repair with the one (and only) tool he happened to have with him. (There's another challenge for you. What tool happened to be in the cockpit? No, not the screwdriver on his Swiss Army knife.) The cowl did not come off in the field.

The engine is injected.

The photos are a little out of order. In the room is the pre-flight briefing. My expression is deep concentration on the briefing mixed with healthy concern/nervousness. Paul has a quote from famed test pilot John Young that I love. It is something like, 'If you aren't a little nervous before the first flight of a brand new aircraft, you don't understand what you are about to do."
I think this experience supports that statement. The field photo was the following morning.

Doors are closing so I have to go.
 
Glad You're Safe...

..and the outcome was good. Incidents such as this should give everyone that's finishing an aircraft a reason to pause and think. Am I qualified to test fly-especially the first few flights? Do I have a good "bail" area that will keep me and the aircraft safe?
My only criticism of this incident is the "guess why" if the answer is already known. Glad the FAA doesn't take this tack when they do accident/incident analysis. The objective should be to get the info out as quickly as possible to help someone else avoid having the same problem.
Terry, CFI
RV9A N323TP
 
Holy cow! Glad you and the airplane are okay. Looking forward to hearing about the presumed cause! :eek:

mcb
 
I like the "guess why" question. It has already shown up other possibilities that can and has caused a total loss of power. Now we all have more than one thing to check before flight on a new aircraft. The answer will come soon enough. Thanks Paul and so glad you and the plane are OK.
 
The Rest of the Story?.

OK folks, that little "information pause" just generated a number of things for all of us to check on our airplanes...didn't it?! Thanks for your patienece - I think the comments and analysis were good. (I liked the logical, methodical approach of the posts - now, can you do that thinking in the time it takes to lose 4,000' in a powerless short-winged RV? )We've had a little sleep (emphasis on little for Louise - she had an 0430 alarm for a business flight this morning...), so here's the deal -and pretty much everything that was guessed COULD have been a possible casue.

IMG_0257.JPG


For those that said fuel Selector, you were right on – or close, depending on if you know the trick to this after-market fuel selector handle. This nice little addition to Van’s standard brass fuel valve has one (known and documented by the manufacturuer) shortcoming – it depends on a set screw to “key” it to the shaft. The standard handle from Van is cast with a solid key in the cylindrical hole so that it can only go on the valve’s shaft one way. But the nice anodized handle works on different vintage valves that have the “flat” of the shaft on opposite sides. You set it up once for your airplane. The countersunk Phillips screw that you see in the picture holds the handle on the end of the shaft, but doesn’t key it. The “flat” on the shaft is very shallow – backing the set screw out by a haf turn will allow the handle to spin on the shaft – rendering the valve useless, and stuck in it’s last position. The instruction clearly state to LocTite the set screw in place….and that is what I mean by the "thousands of details in building one of these planes". In this case, we do so many test fittings and removals; we never know when it will be the last one. So when do you Loc-Tite it? That’s what I hate about red LocTite – you have to be certain you’re done removing it. You never are, so it's easy to forget.

So what Happened to Junior? Well, I was doing laps, breaking in the engine, and it seemed like a good time to switch tanks to keep the tanks balanced. I’ve moved the selector many, many times since final assembly (including during ground engne runs) – but the screw must have been working its way loose, because when I turned the handle, it started to move the shaft, then the set screw slipped off the flat. The handle showed a selected tank, while the valve itself was stuck BETWEEN tanks – essentially in the “off” position. The engine stopped firing shortly thereafter, and nothing I could do would make it run. (The prop kept wind-milling through the flare BTW….) It wasn’t until I was sitting on the ground, waiting for the crew to arrive, that I turned the valve in the silence of the country road, and noted that I didn’t hear or feel that characteristic “click”. It was just light enough to see that the shaft wasn’t turning with the handle. Fortunately, I was carrying an Allen screwdriver that is used to pull avionics – and this set screw was the same size. In two minutes, I had the valve working again – but it was too dark to legally fly, so we waited until morning.

The lesson to be learned is this – no matter how many people inspect the airplane, stuff can (and will) get missed. We are imperfect humans building imperfect machines. Accept that. Plan your flight test ASSUMING (knowing!)that things will fail, and make sure that your backup plans are adequate. Expect the unexpected, and be ready to meet it. That is the mark of a good Flight Test team.

Paul
 
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Great job Guys (and Gal!) w/ plans "b" through "z" and executing on them! The "A Team" for sure. Remember what Hannibal always said at the end of each show? - "I love it when a plan comes together."

Louise said:
What tool happened to be in the cockpit? No, not the screwdriver on his Swiss Army knife.) The cowl did not come off in the field.

For the tool, my guess is a Philips located on the end of the sump draining inspection tool. On mine, I can swap rotate the bit and have a regular/slotted bit but I I don't recall any regular screws on the kits.

The fuel valve idea is interesting. Not being familiar w/ the Junior's exact h/w config, I did go out to the garage and found my old brass fuel value - complete w/ Philips head screw. I removed it and the handle was on pretty tight. I know it's keyed but perhaps it stripped out. Kinda hard for me to imagine that the handle's looseness hadn't been felt prior, though.

Ironflight said:
... but I had no throttle response. I switched tanks several times ...

Hmmm, Paul must be feeling the indent if he believes he's switching tanks.

I'm now not so sure on the fuel valve. Ok, so what else is easily accessible, presumably from the cockpit and presumably w/ a Philips head. Still pondering.....

I got it! "It was all just a bad dream." :D
 
switch terminal came loose ?

It would appear that all the toggle switches have screw terminals on the back. If a screw terminal supplying power to the ignition backed off, and did not go intermitent, this would cause total power loss.
 
Thanks for sharing Paul. I had one of those and the stock valve but decided to switch over to the Andair type later on in the build. Glad you allowed yourself an out and the outcome was a non-issue. Looking forward to seeing Junior at OSH.
 
The newer version of fancy handle for the RV7 has a D shaped pocket for the valve stem. It does not have a set screw.

This may not work on the 3 though depending on how the pointer needs to point.
 
I've always thought about a failure of the fuel selector valve when switching tanks. In fact I've developed the habit of NOT moving it until I have something landable under me. (Preferably paved with a white stripe).

I always chalked this up to natural paranoia. Not anymore.

When you have 7000 airplanes out there making random draws on things every day you will eventually get just about everything to fail.

Good job.
 
Yes, we all make mistakes

Glad your mistake only caused inconvenience. When I installed fuel line on my 10 I must be distracted (how many of us never get distracted? There are other mistakes but they are not as critical.) and failed to tighten it. Although I lost my airplane because of that mistake I am very glad that I was not hurt.

The moral is that we have to be prepared at all time. Anything can happen anytime.
 
Great Job

We used to be in a partnership with a good friend on an older Bonanza. One of the things we carried in the side pocket was a pair of vise grips pre-set to the fuel selector valve shaft. My partner had heard of the handle coming loose on Bonanza's and decreed that we should have the tool on board and handy at all times. I have heard that this is a standard cockpit tool for the P-51 for the same reason. Don't know if that is true.
I am happy with my Andair selector, and it seems like it would be nearly impossible for the selector to come off the shaft, but...................

Paul, you and your team set the standard. Way to go!
 
I've always thought the stock selector had a lot to be desired. The Andair selector is far superior, which is what I have in my -6.

On my Rocket there is no selector. :) All-electric fuel system.
 
I've always thought the stock selector had a lot to be desired. The Andair selector is far superior, which is what I have in my -6.

On my Rocket there is no selector. :) All-electric fuel system.

Nothing wrong with the valve, it was the after market selector handle. I bought one many years ago, but while I was installing it I became uncomfortable with the set screw tolerance. I chose not to install it for that reason.
The instructions call out for that set screw to have lock tight put on it.
Basically, a bad design in my opinion.
Call it build error Paul, but the poor design of the product leaves no room for install error. Had you installed it correctly with the lock tight....no issue. However, that product is an accident waiting to happen as evidence by nearly causing one on one of the most prepared and inspected airplanes built by man!
Great job managing your test flight.
 
Solution

This concept of a little bitty set screw maintaining the correct index sounds like a poor design at best. Seems to me it borders on rinky dink.

Is it possible to drill the selector shaft and the Andair handle for a pin? If not, what is the solution?

Sooner or later it is going to be necessary to switch tanks over hostile terrain. I want more than Loctite between me and potential disaster.

Thoughts?
 
Wow Scary

Congratulations on the first flight as well as dealing with this emergency!

That design is scary indeed. I would drill the shaft for a roll pin or at least a notch for that set screw. I had something similar happen to me while testing the engine on the ground. I didnt loctite (or torque) the center screw on the vans style valve and the entire handle popped off in my hand.
 
Congratulations on the first flight as well as dealing with this emergency!

That design is scary indeed. I would drill the shaft for a roll pin or at least a notch for that set screw. I had something similar happen to me while testing the engine on the ground. I didnt loctite (or torque) the center screw on the vans style valve and the entire handle popped off in my hand.

Ya, but with the standard handle, you can simply put it back on and operate the valve.
Once that set screw backs out of the after market handle, you are done.
 
When the red aftermarket handle 1st became available, I purchased one for my RV6. When my best friend and AP and I examined the way it attached, we became uncomfortable with the system. Even with red Locktite. We ended up putting the handle in position and then inserting a drill through the set screw hole and drilling a hole in the shaft of the selector valve. We then inserted a longer set screw along with Red Loctite. Never had a problem after that fix. After flying with that arrangement for a year we decided that it was too difficult to turn the shorter handle from side to side and went back to the original.
 
Old vintage avionics knobs with setscrews

I've noticed that old ancient (1940's-1960's, etc) avionics knobs made of big chunks of bakelite or machined brass always seemed to have two setscrews in them. One to fill into the "D" portion of the control shaft so it wouldn't slip, and another setscrew 90 degrees around the shaft that was just tightened to brute-force dig into the round part of the side of the control shaft. I'd always thought that was way overkill for holding a knob onto a shaft.

Not anymore.

EDIT: The Andair handle does have the center screw holding it on. I'd probably feel comfortable with the D-screw red-loctited into place. We've got the Andair valve on the RV-8 and I'm unsure if it has the side D-screw in it, or is the later one with a D-shaped pocket... but I guarantee this will be the first thing I check next time I get into the plane.
 
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Is it possible to drill the selector shaft and the Andair handle for a pin? If not, what is the solution?

I don't think the Andair handle needs to be modified, but the red handle that Van's sells is the one in question.

BTW, the Bonanza selector did have a drilled shaft and roll pin, but apparently, the roll pin had been known to break on Bonanzas.
 
RV-3 Flight Number Two

Hmm, when an engine quits it's most likely a problem with fuel starvation or lack of ignition spark. My guess is the mixture went to idle cutoff due to a linkage fault....

Walt Shipley
 
When the red aftermarket handle 1st became available, I purchased one for my RV6. When my best friend and AP and I examined the way it attached, we became uncomfortable with the system. Even with red Locktite. We ended up putting the handle in position and then inserting a drill through the set screw hole and drilling a hole in the shaft of the selector valve. We then inserted a longer set screw along with Red Loctite. Never had a problem after that fix. After flying with that arrangement for a year we decided that it was too difficult to turn the shorter handle from side to side and went back to the original.

Now that is the best solution I have seen yet for this particular handle - drill the shaft all the way through and put a long set screw in there. I have a spare fuel valve, and might just experiment with this.

So a few comments on how we ended up with this handle are appropriate, because everything is clearer in hindsight.

When I built my RV-8, I looked at the that "tractor valve" that came in the finish kit and said "no way I am putting that in my airplane!", so I bought the Andair - a beautiful piece of engineering. I have been totally happy with it BTW. When I started flying Louise's RV-6 (kit #4), I realized that I was flying the tractor valve - and it was working just fine, except that several times, I nearly selected the wrong position, because the HANDLE was indicating the correct tank, rather than the other end - like every valve I had ever used. Since I fly lots of airplanes, this was not a good thing, so when we upgraded her panel and interior, we bought one of these aftermarket valves, assembled it per the instructions (with LocTite), and it has performed just fine ever since - several years, no trouble at all. So when we went on to the RV-3 project, I had experience with the product, knew it's shortcomings...and just missed that Loctite step.

OK, so a few thoughts:

1) Engineers hate designing something that depends on the assembler doing things perfectly because the inspector can't tell how it was done. You can inspect a cotter pin or safety wire - you can't tell if the assembler used one drop of Loctite on a buried set screw. So there is no way to inspect the locking feature, and that makes the engineer nervous! That's why LocTite is the safety method of LAST RESORT for aerospace engineering. it is used, and in critical places - but only when there is no way to design it out.

2) It is wonderful to assume that we can build the perfect airplane, with no faults - pilot proof. If you think you can do that, you're fooling yourself, in my opinion. The pilot ALWAYS needs to assume that things can (and will) go wrong. Don't think "what IF" this fails, but rather "WHEN this fails...." when it comes to having a plan. It was designed by a human, built by a human, and will be operated by a human - do not depend on perfection.

3) Vise grips - yup, that would have solved the problem if I could have gotten the center screw of, then the handle pulled off - ah, but the stick is in the way.... ;) Better to fly the airplane in this case!

4) I thought about using the stock handle last night, but I would have to cut it off to fit in the space we have, and then it would be too short (and poorly shaped) to fit.

5) Remember that the guys building and selling this handle have included instructions warning about this very problem - it was a design choice, not really an ommision. I have been comfortable with it in our other airplane, but folks need to undertsand the risk trade in using it themselves!

6) One improvement to the set screw woudl be to remove the "tapered" end - make the end that contacts the shaft absolutely flat - it woudl have a far bette bearing surface that way.

7) BTW, the handle has to be removeable in order to do any maintenance - assuming that you have the valve behind a panel of some sort. That in iteself complicates makign it foolproof.

8) Finally, you know what they say - make something foolproof, and they'll just invent a better fool....

Paul
 
Nice job getting the aircraft down safely Paul and nice writeup at how you approach test flying.

The standard Andair selector with the standard handle will not be affected even with the screw completely gone as the shaft is machined for 1/2 inch to engage a piece of steel round stock pressed into the handle. If the Van's design left this element out, then that is just a bad design/ copy. The Andair design is sound and extremely well proven.
 
....In two minutes, I had the valve working again ? but it was too dark to legally fly, so we waited until morning.

The lesson to be learned is this ? no matter how many people inspect the airplane, stuff can (and will) get missed. We are imperfect humans building imperfect machines. Accept that. Plan your flight test ASSUMING (knowing!)that things will fail, and make sure that your backup plans are adequate. Expect the unexpected, and be ready to meet it. That is the mark of a good Flight Test team.

Paul

And something else worth thinking of: Paul followed the rules, and didn't try to sneak in a flight home. That's a biggie.

Dave
 
New version of red "fancy" handle...

If the new version of the red fancy handle that's available from Van's is the same item as from Spruce (about $40), then it's now got a D-shaped hole in it instead of a setscrew in the end.

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