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First engine start: Hardware store bolts through spars?

Draker

Well Known Member
I still have my wings attached with long 7/16" hardware store bolts that have the threads ground off. I'd like to make sure there are no leaks anywhere, and no other reasons to pull the wings off, before finally replacing with the proper close tolerance bolts. I don't want to ever have to take those puppies out in the future. What tests can be safely done without the close tolerance bolts? I assume the fuel flow test is fine, but what about spinning the prop to get oil pressure? First engine start? Taxiing? At what point should those tight bolts go in for good?
 
Very Good Question

Very Good Question. Ideally i am in the same boat. i would like to do first engine start with hardware store bolts, and then pull wings and move to flight test airport where I will install proper hardware.
I don't think taxi tests will be good. Also, I think my insurance does not want any movement under own power unless ready for flight (signed off).
 
I think you are fine to do first engine start and everything leading up to that.
I climbed up on my wings in the wing walk area many times without issue. They are not going anywhere.
 
Well, if you're done pulling the wings off, why not go ahead and put the close tolerance bolts in and torque 'em down? What's the downside to putting all of the correct bolts in? Maybe I'm leaning to the side of caution, but I would want ALL of the bolts that hold the wings on if the fuel lines are connected for an engine run. True, if you're just doing a run-up, there's really not much strain on those connections and you could do what you wanted. But if the ground-down hardware store bolts don't have nuts, your connection to the spars isn't as Van's designed and you could potentially have an unintended bending moment around that connection.

Just a thought, but why not wait until everything is about ready to fly, then perform an all up test with all of the connections finalized? After all, you're not going to have to pull the wings if the engine doesn't start. Just make sure you have the nut plates installed on the bottom fuselage skin before calling it a day. But I'm assuming you've got those in and have drilled the rear spar holes in accordance with the instructions.

And yes, check with your insurance carrier to see how they define "not in motion" (builder's insurance) versus in motion or an airworthy aircraft. First engine runs are memorable events, and usually for all the right reasons. But in the unlikely event that something goes south, you want to make sure the insurance has your back.
 
... I'd like to make sure there are no leaks anywhere, and no other reasons to pull the wings off, before finally replacing with the proper close tolerance bolts. ...
As others have said, I don't think at this point you will need to remove the wings to fix anything. I'd put in the final bolts and avoid starting the engine until you are really ready to fly.
 
No problem with the standard bolts... But, engine start should be days before airworthiness paperwork and first flight. Why start the engine before everything else is done? Also, non-broken in cylinders are more prone to corrosion it's said.
 
What would require wing removal at this point? Install the final hardware and be done.
Erich

Worried mostly about fuel leaks from the fitting on the tanks, but now that I think about it, you can remove the tanks without removing the wings, and it's probably easier (?!) Hmm, I'm getting convinced to just put the bolts in now.
 
Me thinks

I as thinking of getting first start done and then pulling wings off and send to paint before first flight
 
Thread drift

Just curious, I’m at the same point as you. What your kit number is? I’m 74775. I like to see where I’m at amongst kit numbers and completions. ;)
 
wait

Try to keep your excitement in check and don't start the engine yet.
I won't comment on what your hardware store bolts will do or not do when you start your engine but my concern is unnecessary engine run up. Checking for leaks in the fuel system is better done by pressurizing the lines than making engine noise.
My concern is based on my own experience where I couldn't wait for a reason not to start the engine and consequently glazed the cylinders during one of those unnecessary run ups which led to burning excessive oil as long as I owned the airplane.
On my second RV, I waited until the very end when all was assembled at the airport and previously tested short of running the engine. I did 2 run ups before first flight and none was more than a couple of minutes and within 2 weeks of first flight.
Do as you wish but I would wait.
 
It is a whole lot easier to paint with the wings off. If that isnt a concern, go for it.

I must have had my wings off at least a dozen times and it was with extra ground down wing bolts that I had. I think you will find even the hardware store bolts will take some sanding to make them go in easier. Having fit them - including the gas lines with easy bolts and replacing them one at a time made worked well for me.
 
Just recall that the wing is stressed for something like 6g plus 50% at max gross weight. Negative g is less but still substantial. The load from it sitting in the ground is a teensy weensy fraction of that. You won’t damage the structure with temporary bolts.

Having said that, I have never seen a good reason to run an engine in the middle of a build other than to satisfy an irrational urge. I have seen guys run their engine in their driveway at home, pissing off the neighbors, creating a safety hazard, then because they are mid build they don’t fly for another 2 yrs. They have then burned off the assembly lube which is great corrosion protection. Pretty much all of the systems can be checked out without running the engine. Pressure sensors, temp sensors, fuel pumps, tank and system leak checks etc. Starting the engine should be just about the last thing you before you fly.
 
Let me chime in with another vote to wait. These engines are meant to be used and the first start starts the clock on negative effects of not being used. An unused engine will collect moisture as it sits and moisture isn't your friend.

My engine builder was adamant that the initial oiling and first engine start be done as close as possible to the inspection, time from pre-oil to first flight should be weeks, not months or years. I understand the urge to see what that expensive beauty can do, but the reality is that there is no good reason to rush to start that engine the first time.
 
i just went the insurance thing. my insurance would cover an engine start as not in motion [builders] but any taxi was in motion and you had to be checked out in my type of plane. after a lot of conversation i was covered for motion but only taxi until i got my check ride.
 
Engine start or no?

Thanks, everyone. Pretty convinced there is nothing stopping me from just getting these bolts done now and checking them off my list. I do plan to get the airplane painted but it will happen after I'm flying. I don't plan to take the wings off to get it painted.

This thread has transformed into a "should I start my engine as soon as I can" discussion. To be honest, I never considered waiting until the very end to first start it up. I just assumed you do it as soon as you have FF done. But looking at my list, most of the project's remaining steps can be done without the spinny thing spinning. I won't be flying until April at the earliest (after transition training), so I suppose there is no hurry.
 
be careful on the -A model

I recall taking it real slow removing the temporary bolts and installing the permanent bolts on my -9A and glad that I did.

The bolts were so tight I had to (air) hammer them in. as soon as the threads appeared on the opposite side i threaded the nut on and drew them up the rest of the way. Had I rammed them in too far, too fast before getting the nut started, the end of the bolt would have been too close to the landing gear bracket to get the nut on, and virtually impossible to drive it back out the other direction (blocked by the bracket). it was a moment of “holy crap” their was a very high probability of this not going good!
 
Yeah, installing the final wing hardware on the -7A really sucks. You can’t complain about it too much however, as it means you are very close indeed to first flight.
 
Yeah, installing the final wing hardware on the -7A really sucks. You can’t complain about it too much however, as it means you are very close indeed to first flight.

Wow, you aren't kidding. Well they're in. This Thanksgiving I am thankful I will never have to do that job again.
 
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