Engine Test Advise

I am finishing up rebuilding my 6A and would like to do a test startup of the
engine before I rivet on the F-671 skin and loose easy access to the area behind my instrument panel. My question is, what needs to be installed before I can safely start the engine?

? I know the wings have to be on but how many of the bolts need to be installed? I need to take the wings off again for painting and I know what a pain it is to install all of the bolts since I have already done that once.
? I plan on clecoing the F-671 skin on which is the only skin not riveted.
? I am unsure if the baggage panels (F-651 and F-652) need to be attached.
? Do I need to attach the rudder and ailerons? The rest of the empennage is attached.
? The canopy will be on.
? I am assuming the cowl does not need to be attached.
? Anything else?

I sent this message to Van's support and received the very cautious and perhaps predictable answer of "We recommend the airframe be complete. It is common to run engines without the cowling on but everything else is finished at that point. You have nothing to gain an to much to loose by rolling the dice on this."

I am not sure what dice I would be rolling if all I want to do is to start the engine to make sure my Light Speed Electronic Ignition is working properly as getting at the box after I finish riveting on the F-671 will be a royal pain. It is located on one side so I could rivet 2/3rds of the F-671 on and cleco the rest.


Thanks,
Ross Mickey
23203
N9PT

You can ask Vans about this, but I would not start the engine with the forward top skin off. The engine transmits torsional forces back to the wing. If you take a paper towel roll and slit it and then compare to one without the slit you will see the role of that skin. It forms the "torque tube" back to the wing spar plane. With out that skin, it is fractionally as stiff, not just a few percent.

It might be ok, but only Vans can really say for sure.

BillL said:

It might be ok, but only Vans can really say for sure.

Click to expand...

Actually they can't know for sure because we have never risked it (which is why he got the answer he already did).
If the only real reason is to test the ign, because it will be so hard to access after the skin is on, then I suggest you re-engineer the installation. Stuff fails. A guaranty you will have to work on that at some point in the future.....

One of the big differences between experienced and non-experienced builders, is knowing how to install/design something to maximize the serviceability later.

Scott is right on board with this. It's actually part of "Murphy's Law".

"If a component is difficult to access, it will fail often."
"The more difficult to access, the more often it will fail or need service."