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Re: Prop Strike
Posted: Wed May 28, 2014 4:53 am
by Waterboy
Well I will make sure the engine is better supported next time it needs to be lifted.
Sounds best to leave the firewall alone and just clean up the old gunk. It sound be flying tomorrow afternoon. Fingers crossed there will be no more delays.
Re: Prop Strike
Posted: Sat May 31, 2014 4:54 pm
by Waterboy
The engine is in and runs great! I flew it for an hour at full throttle yesterday afternoon to start breaking it in. I am very happy with the power output and not a drop of oil leaking.
There are a couple of issues I could use some advice on. The oil pressure ran right at the red line for the entire hour. I am using Aeroshell 100 mineral oil for the break in. The oil pressure line was bled at the gage. Prior to the overhaul oil pressure was always in the normal range. Is high oil pressure normal on an overhauled engine? Our current plan is to watch it for a few hours and see if it comes down.
The other issue, the Alternator would not come on line. It was wired incorrectly on installation. The wire connections were corrected and will still not come online. Could the improper wire connections have fried the Voltage regulator or the Alternator? Thoughts on trouble shooting? Its a Skytronics Jasco 50amp, and worked fine prior to engine removal.
Thanks, Ken
Re: Prop Strike
Posted: Sat May 31, 2014 7:24 pm
by Bruce Fenstermacher
I would not worry a bit about redline high oil pressure. It will only come down as the engine wears and there is really anything you can do about it anyway assuming you have a correct bypass spring and it is within tolerance.
If you find the spring is at fault and a little strong there are probably several people here on the forum who would like to have it.
Re: Prop Strike
Posted: Sun Jun 01, 2014 1:36 am
by johneeb
Bruce Fenstermacher wrote:...........If you find the spring is at fault and a little strong there are probably several people here on the forum who would like to have it.
Yeah! Bluelder, Flyguy, Jrenwick and I would like to have that spring as we could all use a little more pressure (see thread with picture of bar for old guys).
Re: Prop Strike
Posted: Sun Jun 01, 2014 5:19 am
by Waterboy
My red line is marked a 60 psi. I got my normal operating range from the 170 owners manual, 30-40 psi, and it coincides with the green arc on the gage. 60 is within limits so I will not worry about it.
Now we just need to get the alternator online. My mechanic and I will be trouble shooting on it tomorrow.
Re: Prop Strike
Posted: Mon Jun 02, 2014 6:11 am
by cessna170bdriver
My O-300 has run at 55 psi oil pressure for the entire 300 hours I've flown since overhaul with a new relief valve spring. I worried about it at first as well, but all the old heads here on the forum said no problem.
Re: Prop Strike
Posted: Thu Jun 05, 2014 3:17 am
by GAHorn
My 977-hour O-300 has always run at 55 psi. These higher pressures are indicative of close-tolerances on the main bearings. Celebrate. Enjoy.
Zeftronics offers an alternator troubleshooting guide at their website:
http://www.zeftronics.info/documents/tr ... shoot.html
Re: Prop Strike
Posted: Wed Nov 26, 2014 4:41 am
by n2582d
Back to the original topic. The C-145/O-300 8-bolt cranks are getting rarer than hen's teeth. Wouldn't that be a helpful STC if someone could develop an
overload clutch for the O-300 to prevent engine damage in the event of a prop strike? Rotax's 9-series engines have an
overload clutch built into their reduction drives. I guess when the C-145 engine was developed the "overload clutch" was a wood propeller turning to splinters when it hit something solid. My BushHog has a shear pin in the pto drive which helps protect the tractor when (not if) the blade hits a rock. If I wasn't so cheap I'd buy a slip clutch to replace the shear pin. The drawback to an overload clutch would be weight (especially that far forward), cost, complexity, and maintaining the prop at the proper index. I'm assuming that most of the engine damage from a prop strike is due to sudden stoppage rather than the forward/aft bending moment transferred from the prop to the crank. Thoughts from the engineers out there and the engineer wannabes?
Re: Prop Strike
Posted: Wed Nov 26, 2014 12:48 pm
by edbooth
gahorn wrote:My 977-hour O-300 has always run at 55 psi. These higher pressures are indicative of close-tolerances on the main bearings. Celebrate. Enjoy.
Or an oil pressure gauge out of calibration .
Zeftronics offers an alternator troubleshooting guide at their website:
http://www.zeftronics.info/documents/tr ... shoot.html
Re: Prop Strike
Posted: Wed Nov 26, 2014 1:27 pm
by sfarringer
n2582d wrote:Back to the original topic. The C-145/O-300 8-bolt cranks are getting rarer than hen's teeth. Wouldn't that be a helpful STC if someone could develop an
overload clutch for the O-300 to prevent engine damage in the event of a prop strike? Rotax's 9-series engines have an
overload clutch built into their reduction drives. I guess when the C-145 engine was developed the "overload clutch" was a wood propeller turning to splinters when it hit something solid. My BushHog has a shear pin in the pto drive which helps protect the tractor when (not if) the blade hits a rock. If I wasn't so cheap I'd buy a slip clutch to replace the shear pin. The drawback to an overload clutch would be weight (especially that far forward), cost, complexity, and maintaining the prop at the proper index. I'm assuming that most of the engine damage from a prop strike is due to sudden stoppage rather than the forward/aft bending moment transferred from the prop to the crank. Thoughts from the engineers out there and the engineer wannabes?
A drawback that you didn't mention: It would be something else to go wrong.
I believe I would rather try to avoid hitting something with my prop.
Re: Prop Strike
Posted: Wed Nov 26, 2014 4:18 pm
by bagarre
+1
I don't think prop strikes are so common that they require such a complicated solution.
That and I don't know how effective it would be. Sudden stoppage isn't the only way to damage an engine in a prop-strike.
Who's to say the counter weight bushings wont be damaged with the force required to slip the clutch?
Re: Prop Strike
Posted: Wed Nov 26, 2014 4:49 pm
by bagarre
I keep a vixen file on hand so I can smooth out the notches before anyone notices.
If it's bent you can get them pretty straight with a block of wood and a mallet.
Re: Prop Strike
Posted: Wed Nov 26, 2014 10:25 pm
by ghostflyer
Just came back from the hangar and while I was there had a look at the old fire wall that was removed. It is a zinc coated mild steel sheet. Some of the previous comments listed raised my interest . When we replaced the fire wall it was noted some clown had tried to solder a earth lead on to it. Plus it had so many patches[patches on patches trying to cover missed drilled holes] and holes in it. It was a just too ugly. so a stainless steel one went in and besides being riveted in it was bonded in to stop oil flowing into the cabin area. The old Continental had a number of oil leaks. you would fix one and another one would start. In flight I could smell engine oil and it was flowing back on the underside of the outside skin.
OOPS this is not supposed to be in this area, it will not let me move it.
Re: Prop Strike
Posted: Thu Nov 27, 2014 3:10 pm
by wingnut
bagarre wrote:I keep a vixen file on hand so I can smooth out the notches before anyone notices.
If it's bent you can get them pretty straight with a block of wood and a mallet.
I hear a story, years ago
about one of the business owners (in the early years of this airport). Leo Overturf would purchase and repair derilect and damaged planes. There were more liberal tolerances on bent blades back then. So, if the prop blades were bent beyond that tolerance which would allow a prop shop to legally straighten, Leo would straighten them to that "maximum allowable" bend before he sent them to Herman Foster in Wainwright OK for repair/overhaul. Leo's method was simple. Behind the hangar was a twin pine tree (a pine tree that forked very close to ground level, and each side grew up close to parallel, except the gap would get slightly larger as you "progressed" in the straightening process. When satisfied that the prop blades were now within repairable spec, Leo would deliver the prop to Herman Foster via plane and pilot. Herman had a grass strip at his then remote prop shop. After several years of this, Herman finally sent word to Leo that he could no longer accept any props from Mena Arkansas "until somebody at least cleans the damn pine sap off 'em"
All parties are long gone, and the elders seem to all have their own variation of the story. The pine tree is still here, and shows clear signs of having been molested many moons ago. Herman's son Jerry runs a tight ship now and will not tolerate anything of this sort. The grass strip has long since been just a hay field. Herman's widow still answers the phone and is a sweetheart to talk with.
Sorry for the hijack. Just brought back a memory.
Re: Prop Strike
Posted: Thu Nov 27, 2014 10:18 pm
by blueldr
Sounds like Leo was my kind of guy.