Prop Strike
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Prop Strike
Our 182 suffered a prop strike after making an unplanned excursion off the taxiway onto some very muddy ground at the weekend. The nose wheel dug in and the prop sliced through the mud causing a small but clearly noticeable bend to one of the blades.
We're now in the process of working with our insurers and maintainers to get the engine and prop sent off for testing / repair / replacement. I've got a few questions which Im hoping someone can help with.
Can/should the prop be repaired ? There doesnt seem to be any damage to the tips only a slight bend.
If the prop needs to be replaced is it worth thinking about a 3-blade model? Any idea of the rough difference in cost?
The engine is 10 years old and has just over 600 hours on it. Should we consider using this as an opportunity to have the engine zero-timed?
Anything else we should be thinking of?
many thanks
140kias although currenty zero-kias for the foreseeable future
We're now in the process of working with our insurers and maintainers to get the engine and prop sent off for testing / repair / replacement. I've got a few questions which Im hoping someone can help with.
Can/should the prop be repaired ? There doesnt seem to be any damage to the tips only a slight bend.
If the prop needs to be replaced is it worth thinking about a 3-blade model? Any idea of the rough difference in cost?
The engine is 10 years old and has just over 600 hours on it. Should we consider using this as an opportunity to have the engine zero-timed?
Anything else we should be thinking of?
many thanks
140kias although currenty zero-kias for the foreseeable future
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If you have had a prop strike its normal to have the engine stripped down and inspected for shock load damage. Your engineers will advise about the merits of repair - your insurers may just go for a replacement. Leave it to them to sort out
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Very sorry to hear. I had a prop strike (pothole during taxi) in 2002, with just 1 hour on the clock... I am quite careful with grass these days, as a result. Not because grass is a problem but because it tends to go with a "lesser" attitude to airfield maintenance.
An engineer should give you the legal verb on that but you should not do it. Change the blade. If a piece of a blade comes off, you will definitely know about it, and the engine could come off rapidly, very soon afterwards.
Depends on the prop. Quite a lot of people have done that. There is unlikely to be a perf improvement but it looks a lot better 
However, the Hartzell 3B props have a tougher rule on prop strikes than most 2B props. From vague memory, if you have to remove 2 or 3 blades for any reason (for repair) then the hub has to be scrapped, and economically this means they sell you a whole new prop
In my case, the prop was £11k with a JAR-1 form, or US$9k with an 8130-3, and the latter was perfectly fine for the G-reg it then was. But the word "insurance" means much the same in aviation as in the car trade i.e. everybody rubs their hands. I got the £11k prop...
You will have to NDT the hub anyway, even if you fit 2 new blades. Plus overhaul the governor (which includes an NDT of that too). Plus overhaul the magneto(s). All these bits can get shock loaded.
I would say No but it depends on its condition, obviously. They will let you know how good/bad it is when they open it up and strip it all down for NDT, anyway.
They may find corrosion. 600hrs in 10 years is plenty of hours but also could mean some long standing around.
Anything short of an "overhaul" is a "repair".
Use a competent engine shop, not the usual cowboys which dominate the UK scene I sent my engine to Barrett Precision (for the SB569 job) which is perhaps the most reputable shop in the USA but you can't do that if you are on G because BP cannot issue a dual-released 8130-3. You will have to use some UK shop, or one of the bigger US ones like Pen Yan, etc.
Make sure the shop knows about balancing the weights, etc. A pilot has just emailed me to say his engine was rebuilt and is shaking quite badly; 0.8 IPS on the dynamic prop balancer which is verging on unairworthy; I guess they forgot to match up the opposite pistons / conrod small ends or whatever.
Can/should the prop be repaired ? There doesnt seem to be any damage to the tips only a slight bend.
If the prop needs to be replaced is it worth thinking about a 3-blade model? Any idea of the rough difference in cost?
However, the Hartzell 3B props have a tougher rule on prop strikes than most 2B props. From vague memory, if you have to remove 2 or 3 blades for any reason (for repair) then the hub has to be scrapped, and economically this means they sell you a whole new prop
In my case, the prop was £11k with a JAR-1 form, or US$9k with an 8130-3, and the latter was perfectly fine for the G-reg it then was. But the word "insurance" means much the same in aviation as in the car trade i.e. everybody rubs their hands. I got the £11k prop...
You will have to NDT the hub anyway, even if you fit 2 new blades. Plus overhaul the governor (which includes an NDT of that too). Plus overhaul the magneto(s). All these bits can get shock loaded.
The engine is 10 years old and has just over 600 hours on it. Should we consider using this as an opportunity to have the engine zero-timed?
They may find corrosion. 600hrs in 10 years is plenty of hours but also could mean some long standing around.
Anything short of an "overhaul" is a "repair".
Anything else we should be thinking of?
I sent my engine to Barrett Precision (for the SB569 job) which is perhaps the most reputable shop in the USA but you can't do that if you are on G because BP cannot issue a dual-released 8130-3. You will have to use some UK shop, or one of the bigger US ones like Pen Yan, etc. Make sure the shop knows about balancing the weights, etc. A pilot has just emailed me to say his engine was rebuilt and is shaking quite badly; 0.8 IPS on the dynamic prop balancer which is verging on unairworthy; I guess they forgot to match up the opposite pistons / conrod small ends or whatever.
I had a prop strike in soft ground at Peterlee in C182Q whilst taxying.
Minor damage to outer 1cm of prop tips,engine did not stop
Required shock load inspection and new prop/hub
Engine only had 200 hours so cannot comment on whether to overhaul your engine
Fitted 3-blade prop - much better ground clearance and I think better performance (also looks cool!)
Insurance company were excellent. New 3 blade prop was actually cheaper than 2 blade(?!) and because original prop/engine had only 200 hours there was little 'betterment' to pay
As I was 150 miles from base you learn the importance of having a good working relationship with your maintenance organisation - mine had the engine out within 24 hours of the incident (plus all the avionics as a precaution!) The insurance company were not prepared to cover the cost of derigging and transporting to home airfield.
Talking to C182 owners with 2-blade props there seems to be those who have had a prop strike and those who are going to have one!!
Safe flying
G-BHIB
Minor damage to outer 1cm of prop tips,engine did not stop
Required shock load inspection and new prop/hub
Engine only had 200 hours so cannot comment on whether to overhaul your engine
Fitted 3-blade prop - much better ground clearance and I think better performance (also looks cool!)
Insurance company were excellent. New 3 blade prop was actually cheaper than 2 blade(?!) and because original prop/engine had only 200 hours there was little 'betterment' to pay
As I was 150 miles from base you learn the importance of having a good working relationship with your maintenance organisation - mine had the engine out within 24 hours of the incident (plus all the avionics as a precaution!) The insurance company were not prepared to cover the cost of derigging and transporting to home airfield.
Talking to C182 owners with 2-blade props there seems to be those who have had a prop strike and those who are going to have one!!
Safe flying
G-BHIB
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It's very true that a 3B prop should have a better ground clearance. On my plane it is an extra 1" clearance.
You could say that about just about anybody.
A C182 is used to go to grass strips, due to its short field performance, but it still has a propeller on the front of it...
Talking to C182 owners with 2-blade props there seems to be those who have had a prop strike and those who are going to have one!!
A C182 is used to go to grass strips, due to its short field performance, but it still has a propeller on the front of it...
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Engine overhaul in the UK
Peters view on UK engine overhaulers is somewhat bleak but has a basis in truth, there are a lot of indifferent engine shops in the UK and Northern Europe.
On the bais of 20 years in the maintenance business I would recomend Nicolson Macclaren or Eisenburg both I deal with on a regular basis, another guy in the Wokingham area seems to be getting good reviews but I cant for the life of me remember his name.
The rest of them are not realy worth bothering with and dont be tempted to use a very atractivly priced outfit in Denmark they are probably the worst engine shop I have ever had dealings with. My experience with them is a 100% failure rate before 600 hours.
There is a cost of doing a job properly and that is why you are unlikely to be able to slide a cigarette paper between a quote from N-M or Eisenburg...........anything cheaper is likely to be rubbish.
On the bais of 20 years in the maintenance business I would recomend Nicolson Macclaren or Eisenburg both I deal with on a regular basis, another guy in the Wokingham area seems to be getting good reviews but I cant for the life of me remember his name.
The rest of them are not realy worth bothering with and dont be tempted to use a very atractivly priced outfit in Denmark they are probably the worst engine shop I have ever had dealings with. My experience with them is a 100% failure rate before 600 hours.
There is a cost of doing a job properly and that is why you are unlikely to be able to slide a cigarette paper between a quote from N-M or Eisenburg...........anything cheaper is likely to be rubbish.
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I agree with the two names mentioned by A&C being regularly recommended by happy customers.
One reason I went to the USA for my job was that nobody in the UK was authorised to dynamically balance crankshafts.
One reason I went to the USA for my job was that nobody in the UK was authorised to dynamically balance crankshafts.
The C182 is an excellent all-round aeroplane (I'm biased after 15 years ownership and @ 1200 hours on type).
However there are a few 'gotchas' as with any aeroplane : the combination of a forward c of g, 2 blade prop and slightly underinflated nose oleo makes a prop strike more likely than on other aircraft. Overinflating the nose oleo is not recommended as it makes manouvering on the ground difficult due to limited nose wheel steering. A 3 blade prop with better ground clearance is definitely he way to go.
G-BHIB
However there are a few 'gotchas' as with any aeroplane : the combination of a forward c of g, 2 blade prop and slightly underinflated nose oleo makes a prop strike more likely than on other aircraft. Overinflating the nose oleo is not recommended as it makes manouvering on the ground difficult due to limited nose wheel steering. A 3 blade prop with better ground clearance is definitely he way to go.
G-BHIB
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We had a 'prop strike' on a three blader in an Arrow (due to pilot omitting to remove towbar.)
The propellor was destroyed : needed entirely new prop/hub, but the engine was not shock loaded.
The engine had been on condition due age at 1800 hrs so paying for a rebuild was a no- brainer.
And after 25 hours the engine is now running smoother than it ever did.........
The propellor was destroyed : needed entirely new prop/hub, but the engine was not shock loaded.
The engine had been on condition due age at 1800 hrs so paying for a rebuild was a no- brainer.
And after 25 hours the engine is now running smoother than it ever did.........
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but the engine was not shock loaded.
It's true that with nearly all shock load inspections, no damage is found.
The problem is that one cannot detect subsurface cracks with the dye penetration methods used.
A close friend of mine had an unplanned connection with his tow bar resulting in a 25mm radius being filed on the tips (metal fixed pitch, all approved by prop-shop).
The aircraft now goes 7kt faster at the same RPM
It's an ill wind ......
The aircraft now goes 7kt faster at the same RPM
It's an ill wind ......
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I'd put on the 3 blade. Hartzell do a Top Prop conversion for the 182.....For our Commander, ours cost ~£7500 inc VAT delivered via Proptech in portsmouth. The same TopProp from the USA was about $10500 + shipping + VAT so it was cheaper to get it in the UK. Gives about 3 inches better ground clearance, and looks much better and the scimitar blades are meant to be quieter.
I'd get a new prop, no question. The shock load test for insurance purposes will probably be 5 grand, and a rebuild say 20,000. If you could offset the 5k against the 20k then it might be worth considering a zero times overhaul at NMA? But iif the engine is ok, then I suppose you have spent an extra 15k for nothing....?
I'd get a new prop, no question. The shock load test for insurance purposes will probably be 5 grand, and a rebuild say 20,000. If you could offset the 5k against the 20k then it might be worth considering a zero times overhaul at NMA? But iif the engine is ok, then I suppose you have spent an extra 15k for nothing....?
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[quote]Quote:
but the engine was not shock loaded.QUOTE]
Going by the findings of one of the best Engine re-builders in the Country: (Eisenberg)
As the pilot cut the engine at 50 ft before landing the engine was delivering no power and the blades were windmilling and slowing down.
Agree sub surface cracks not detectable but less likely than if engine was going at full power and suddenly stopped by obstacle.
but the engine was not shock loaded.QUOTE]
How could you be sure?
T
It's true that with nearly all shock load inspections, no damage is found.
The problem is that one cannot detect subsurface cracks with the dye penetration methods used.
T
It's true that with nearly all shock load inspections, no damage is found.
The problem is that one cannot detect subsurface cracks with the dye penetration methods used.
As the pilot cut the engine at 50 ft before landing the engine was delivering no power and the blades were windmilling and slowing down.
Agree sub surface cracks not detectable but less likely than if engine was going at full power and suddenly stopped by obstacle.
Last edited by Cusco; 24th Mar 2012 at 21:39.
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Many thanks for all the extremely helpful advice. Our maintenance company has prepared an estimate for the insurance company. The have quoted the following shops;
Engine - Aero Engineering and Powerplant
Prop - General Aero Services
I'd appreciated any feedback on either of these organisations.
Our 182 is an RG model with a Lyco O-54-J engine and McCauley VP prop. Looking at the Hartzell website they dont seem to cover our engine or am I missing something.
Ive also read in the past about vibration being an issue with a 3B. Is that all down to proper balancing?
Engine - Aero Engineering and Powerplant
Prop - General Aero Services
I'd appreciated any feedback on either of these organisations.
Our 182 is an RG model with a Lyco O-54-J engine and McCauley VP prop. Looking at the Hartzell website they dont seem to cover our engine or am I missing something.
Ive also read in the past about vibration being an issue with a 3B. Is that all down to proper balancing?
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For some reason, 3B props have suffered from vibration more than 2B props - at least on some aircraft types.
Dynamic balancing is highly desirable. It costs a few hundred quid. I used to use Worldwide Aviation at Bournemouth but I don't know if they still do it; I heard the man in charge retired a while ago.
I did a little test here but didn't get before/after data.
Dynamic balancing is highly desirable. It costs a few hundred quid. I used to use Worldwide Aviation at Bournemouth but I don't know if they still do it; I heard the man in charge retired a while ago.
I did a little test here but didn't get before/after data.
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another guy in the Wokingham area seems to be getting good reviews but I cant for the life of me remember his name.
NoD
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+ 1 for Neil Andrews, a good few of the engineers I've used over the last couple of years recommend him for personal work. He did a nice/simple/reasonably priced top end overhaul for me a couple of years ago following bore corrosion on an underused engine. Equally Eisenburg did a good overhaul on the engine 11 years ago, O320B2B dynoed at 167hp 