MartinPred

MartinPred

Well Known Member
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ALCON:

I'm afraid we just had a bit of an incident with My RV-4, the Lemon Squeeze. Good news: no injuries. Both me and my passenger walked away.

Bad news: prop strike resulting in shattered prop and engine stoppage, bent tailwheel fork as a result of coming back down pretty hard, and a fair amount of cracked fiber glass.

Secondary good news: insurance is paid up and I have no reason to expect we won't be covered in full. So here's a few questions for you.

- We'll have the engine taken apart and fully inspected. What sort of damage should we make sure to look for?

- If we end up getting a new engine, should we go with the same O-360-A1D or something else?

- Can fiber glass be repaired or does it need to be replaced? We have damage to upper and lower cowls, and both wheel pants. What's the best way to get those parts back up to speed?

- Anything else we should be working on?

Thanks,

-Matt
402BD
 
Sorry to hear, If you don't mind, when everything gets settled down, could you share what happened?

david
 
I assume the cowl got creamed when the prop hit the ground. If the engine moved enough to wreck the cowl, I'd take a good look at the engine mount. I'd also take a close look at the tailgear weldment and the weldments on the back of the firewall. Fiberglass can be fixed quite easily, and would probably be easier than fitting a new cowl and pants.

Glad everybody is ok.
 
Matt,
First of all, I think I can write for all of us that the best possible result is that you nor your passenger were hurt.

The great thing about a wood or fiberglass prop is that it sacrifices itself and saves your engine.....its a good idea to have the engine inspected but there will not likely be any damage.

The fiberglass parts can all be repaired if not totally destroyed.

You should very carefully inspect every part of the fuse, empennage and wings looking for buckled skin and bulkheads, popped rivets etc so needed repairs can be made.

Good Luck....Hope everything checks out OK.

Glenn Wilkinson
 
Engine Prop Strike Inspection

Matt:

Sorry to hear about your incident, but glad that no one was injured.

Here's what our engine shop does at teardown inspection for sudden stoppage. Cold compression check prior to teardown. If they are good, we do not access the cylinders. Complete teardown, check the run out on the crankshaft, mag particle of components, 500 hour magneto inspection, replacement of all mandatory replacement parts at access (bearings, gear attaching bolts, all gaskets and locking devices, pin plugs, mag cushions, rod bolts and nuts, thrust buttons, ct'wt washers, drain hoses), crankshaft balance, paint, assemble and one hour dyno test.

Specifically, we are looking for damage to the crankshaft and gear attaching bolts at inspection, but the majority of the time it is a precautionary measure. More commonly, we find scoring on the bearing journals of the crank and frequently corrosion on the cam/lifters (if it is a flat tappet engine.) When we find that, we must have the crank polished and/or reground if it is still within serviceable limits. The same goes for the cam. We always use new lifters rather than repaired. If you have a Lycoming roller tappet engine, there are some other considerations with the tappets. We also make sure that all ADs and SBs are in compliance at return to service.

Hope this is helpful to you. Good luck.
 
Couple things to look at on the -4's after a "firm" arrival (if I'm interpreting correctly). Look specifically at the engine mount where it connects to the footwell on the firewall and look very carefully for any wrinkles/crinkles on that area of the firewall. Look very carefully at the lower engine mount weldments and the side skins for any wavy/wrinkly at all. If you see a wrinkle/wave/crinkle in any of those areas, then it's time to start taking 'er apart.

Also, look very cloesly (with a bright lights/magnifying glass) at the HS stab attach points. I've seen a number of cracked ones after incidents similar to yours - specifially the outer sides of the bolt holes towards the flanges of the spar.

As far as the cowl goes, it can be repaire, but if the damage is significant and the cowl is the old gel coat type, sometimes it can be easier to start from new.

Anyway, those are the main things I'd look at. The firewally is a weak point in the -4's, and with a 360 hanging on the front the mount/firewall or main longerons up there usually suffer some damage, even if you don't see it. We've done a lot of work on -4's over the years, and have almost re-built some from the ground up after damage, so I can say that almost everything can be repaired. Just depends on time/money, etc..

If the prop was glass or wood, then that's a bit of a different story when it comes to the engine.

My 2 cents as usual.

Cheers,
Stein
 
MartinPred said:
ALCON:
Bad news: prop strike resulting in shattered prop and engine stoppage, bent tailwheel fork as a result of coming back down pretty hard, and a fair amount of cracked fiber glass.
- Anything else we should be working on?

Thanks,

-Matt 402BD
Click to expand...

It sounds like you dropped back onto the tail after going up on the nose?
...Not uncommon .
The tailcone, aft of the F-410 bulkhead alsneeds to be carefully inspected. Particularly in the F-411/ F-412 region. A very high vertical load can be transferred through the tail spring weldment.
 
Matt,
I'm glad all are safe.

Besides the engine manufacture's having prop strike inspection criteria's all governor manufacture's have a teardown - inspection (overhaul) criteria in place.

Hope all goes well with the inspections.

Bob
 
Engine Options

Now that the dust has settled, here's an update:

Insurance is covering everything and repairs are underway. :) We're going to replace the engine mount, gear struts, firewall, tailwheel fork, prop, and of course, repair all the fiber glass.

Here are some photos from the mishap:

PropStrike1.jpg


PropStrike2.jpg


PropStrike3.jpg


Instead of replacing the Sensenich wood, we're thinking about ordering a Catto three blade.

The estimate for the engine teardown inspection was $6,500. But my old O-360-A1D was getting pretty tired. The last overhaul was 20 years ago. She was burning a quart or oil every three or four hours, and the compression was down in the 60s. So rather than have the engine inspected and repaired, I'm thinking about using that cash towards a replacement.

So here's a question for all of you: overhaul the engine, exchange the core for a factory re-man, or exchange it for a freshly-overhauled one?

Any lessons learned in this area would be appreciated.

-Matt
402BD
 
glenn654 said:
Matt,
The great thing about a wood or fiberglass prop is that it sacrifices itself and saves your engine.....its a good idea to have the engine inspected but there will not likely be any damage.Glenn Wilkinson
Click to expand...

Glenn, the post did say he had a stoppage, so there is a possibility of some engine damage.
 
MartinPred said:
Now that the dust has settled, here's an update:

Insurance is covering everything and repairs are underway. :) We're going to replace the engine mount, gear struts, firewall, tailwheel fork, prop, and of course, repair all the fiber glass.

Here are some photos from the mishap:

PropStrike1.jpg


PropStrike2.jpg


PropStrike3.jpg


Instead of replacing the Sensenich wood, we're thinking about ordering a Catto three blade.

The estimate for the engine teardown inspection was $6,500. But my old O-360-A1D was getting pretty tired. The last overhaul was 20 years ago. She was burning a quart or oil every three or four hours, and the compression was down in the 60s. So rather than have the engine inspected and repaired, I'm thinking about using that cash towards a replacement.

So here's a question for all of you: overhaul the engine, exchange the core for a factory re-man, or exchange it for a freshly-overhauled one?

Any lessons learned in this area would be appreciated.

-Matt
402BD
Click to expand...

My vote, if you can afford it, replace it with a new engine, little more power and than smile ear to ear when it's done.
 
Prop Strike Experience

Wheel landing, 50% of runway closed for maintenance and fresh tar on cracks in remaining open runway results in a "nosie"! I've got experience that is about 4 years old. (I was at a relatively slow speed when this occurred.)

I ended up in sort of a tripod situation - (1) the two main gear wheel pants, (2) lower cowl air intake and (3) two blades of my Catto 3 blade prop which had at most only the first 6 inches chewed up.(My tail was sticking in the air and my nose was within inches of center line).

Because the Catto prop is considered "wood" (i.e., composite over wood core) the first engine check is a "dial" check of the engine flange. If no bend to the crank shaft, no need to go further except to check and replace as necessary the components of the accessory gear case. For me, everything checked "OK". Checked firewall, etc. and no other issues. I had the prop bolts magnafluxed and got a new prop from Craig Catto. All fiberglass repaired and all worked fine. (I also have this great conversation piece hanging on my wall - the remains of prop.)

My engine only had about 450 hours on it so I did nothing additional at that time. Insurance covered the whole repair (at most about $4,000 including the cost of a new prop.)

Since then I sent my engine in for new hi compression pistons and a new oil sump (together about 12 additional hp). Looking at the insides of my engine, the engine repairer said everything looked fine.

That's my experience, yours may very. Check everything that looks suspicious.
 
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Prop strike - stoppage

I'm currently dealing with prop strike-engine stoppage on our Pitts, with bent tail spring from tail coming back down hard (like yours). One additional change recommended in our case (and paid for by the insurance) was a new prop governor. If you had a CS prop this might be a consideration. Our shop felt the Lord mounts needed replacing also and the insurance paid part of this cost - prorated vs. engine o'haul hours. Hope you are back flying soon! Bill
 
You may also want to make sure your gear legs are not bent. If you came down real hard there is a chance they are bent just a little.

It is probably not critical as they are just big springs that are meant to bend and flex quite a bit, but you may find the plane tracks 'funny' when on the wheels or it may wear the tires in an odd manner (or at least differently than it used to).

I am sure you can give the guys at Langair a call and they might be able to help you identify if they are bent.
 
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