The International Cessna^® 170 Association

Jim...get the C/S if that's what it takes to get you out of the usual short haul missions and into the annual trek to the convention missions!

Miles,

No wonder my check book is so screwed up!

The only reasons that I never fited a CS prop on my airceaft when I fitted the O-360 was Cost, Extra weight and the C of G was too far forward and plus complexity of a CS prop. I have flown both types of aircraft [a fixed pitch /CS prop] ,while the CS is easier to fly ,I found the takeoff performances very similar. However all brands of fixed pitch props are not. I seemed to get more out of the Sensenich prop than the Mc Cauley . The Sensenich is a much better cruise prop. For climb ,they are both about the same. Both props were 60in pitch. One issue is that i have is due to the hollow crankshalf ,I have a RPM nogo zone of between 2250 and 2450 due to hymonics. I have learned to fly around this.
Last week it was 37 deg C and that really affected takeoff performance. Thats where a CS prop would have been helpfull. It was only me in the aircraft and half tanks.

I may have posted this in the past so please excuse me if I'm repeating myself. The differences in weight is very minimal, if there was a great difference as some attest, the Lycoming conversion would be a lawn dart.
The real difference (20 lbs.) in prop weight, (recouped in other areas) is the ARM of the weight which does make a difference. Having said that my aircraft operates within the C go G limits and I believe it would be difficult to get these conversions approved if they did not fall within limits.
A forward C of G is not a bad thing and seeing the I/O 360 with C/S in either a Hawk XP or a XP conversion (T.A., when it was available), is a manageable combination, I would think so would a 170 type with a Lycoming.
Yes, a valid argument about the differences in; battery size, location, components there and not there, engine weights, prop weights is valid, overall in the end you gain some and lose some, but the net increase in weight is minimal.
The climb performance cannot be compared as equal.
The RPM limitation is for some constant speed propellor/ engine combinations; does the STC specifically state a limitation when a fixed pitch is installed? Why would it apply to a fixed pitch ? I think if Harry was still with us, he would have a simple answer.

Bruce Fenstermacher wrote:Jim,

You really haven't told us much about this engine. What is it's recent history?

Sounds like you have some log book investigation to do. A 50 year old carb that is working has only one Ad to comply with that I can think of and that is the two piece venturi. And this is just a 100 hour inspection unless the venturi is loose. There were float and needle ADs which you need to review but I believe those all resolved themselves eventually that the original stuff was ok. But again you need to do do diligence and review your log history and the course of each AD. You can do this yourself and present a detailed history and findings to a mechanic and save him some time.

The mags will also need to have a log investigation. You did not say what mags you have. Makes a difference when it comes to ADs. The Scintilla (Bendix) SF6LN-12 have no ADs the much more popular Bendix S-20 series have a few and some that have come and gone. Certainly if no one has looked inside the mags since 1981 it is due.

Harnesses can be tested and leads replaced as necessary. You don't even have to remove the cylinder to fix a leaky exhaust valve if you find the right mechanic and intake hoses always look worse than they are.

The "recent" history as follows:

Engine total time 2075 hrs.
Mags overhauled 1981, 125 hours ago
Top overhaul 1969, 346 hours ago.
New rings and honed cylinders 1964, 615 hours ago
Major overhaul 1963, 707 hours ago
Compression checks - #5 generally lowest with April 2013 value 66/80.
Carb and Mag ADs appear to be complied with.

Jim

Generally other than calendar time since these overhauls, the time in service looks good.

So the question is how often and consistently has this engine been run? Has it been run a 1/2 hour every month since the top overhaul? If so the engine will be fine. If it was run 346 hrs from '69 to '74 and then sat since then the picture is much much different. If the engine sat for long periods, say a year, then operated fine for say a 100 hours and there was no ill effects then chances are good that period of inactivity had no ill effects. What causes ill effects is rust. If the engine did not accumulate any while inactive, it won't know the difference. If it does them when run the rust can wipe out cams, lifter bodies and cylinders first most likely and then perhaps at the same time the rust and wear metal it created circulating wipes the bearing and the crank.

These engines can stand periods of inactivity. And where and how it was stored makes a big difference.

So history, and recent history has to include the activity level or lack there of.

BTW two of my cylinders measured out at 66 over 80 this annual. One I couldn't tell where it was leaking the second through the exhaust. Probably both are exhaust leaks. I'm not planning to do a darn thing about it at this point. If I checked them today they are likely to be different and higher.

To answer Jims question, Sensenich does have RPM limits on the fixed pitch range as per there web page. I was between a rock and a hard place where i placed the battery as this effected the c of g range. It ended up on the fire wall due to accessability . it was a headache to put it in the tail.and putting lead weight on the tail wheel wasnt my cup of tea either.

jimnh20 wrote: I currently have 180 gear legs with Pponk attachments Cleveland wheels, double-puck brakes, and 8X6 tires and a Scott tail wheel. Although the tail wheel assembly has been rebuilt and the alignment of the main gear has been adjusted, landing and roll-out is a serious adventure - not at all as stable as a stock 170.

Jim, I thought of your recent post when I ran across this NTSB report which is about an accident of a C-170 with gear modifications similar to yours. Any of you Alaska guys have further details into this accident?

GF, read the SB for the prop limitation, thks for that info.

quote="jimnh20"] I currently have 180 gear legs with Pponk attachments Cleveland wheels, double-puck brakes, and 8X6 tires and a Scott tail wheel. Although the tail wheel assembly has been rebuilt and the alignment of the main gear has been adjusted, landing and roll-out is a serious adventure - not at all as stable as a stock 170.[/quote]

n2582d wrote:[Jim, I thought of your recent post when I ran across this NTSB report which is about an accident of a C-170 with gear modifications similar to yours. Any of you Alaska guys have further details into this accident?

Thanks Gary - Doesn't make me feel a lot better about the mods, but gives me some hints about adjustments.

Jim

Generally other than calendar time since these overhauls, the time in service looks good.

Bruce Fenstermacher wrote:So the question is how often and consistently has this engine been run?

Has it been run a 1/2 hour every month since the top overhaul? If so the engine will be fine. If it was run 346 hrs from '69 to '74 and then sat since then the picture is much much different. If the engine sat for long periods, say a year, then operated fine for say a 100 hours and there was no ill effects then chances are good that period of inactivity had no ill effects. What causes ill effects is rust. If the engine did not accumulate any while inactive, it won't know the difference. If it does them when run the rust can wipe out cams, lifter bodies and cylinders first most likely and then perhaps at the same time the rust and wear metal it created circulating wipes the bearing and the crank.

These engines can stand periods of inactivity. And where and how it was stored makes a big difference.

So history, and recent history has to include the activity level or lack there of.

BTW two of my cylinders measured out at 66 over 80 this annual. One I couldn't tell where it was leaking the second through the exhaust. Probably both are exhaust leaks. I'm not planning to do a darn thing about it at this point. If I checked them today they are likely to be different and higher.



The answer is very inconsistently - the engine has undergone very long periods of inactivity. I think I will get #5 pulled and the oil drained and tested (along with visual of filter) while attending to the exhaust valve - #5 has always seemed to be a problem child in this engine's life. Do a borescope of the cylinders and also the bottom end through the drainplug looking for rust and other signs of internal damage. Although there are not a lot of hours on the mags, I think I will perform an inspection and rebuild, if visual observation indicates that is the appropriate course due to age. Per advice given earlier, I will ask the mechanic to test the wiring harness before replacing. Same for hoses. The idea is to get the plane back in the air; fix or replace the gear; then depending upon findings in the engine compartment, look into an O-360 replacement.

As always - willing to hear sage advice from the denizens..... Anything else I should look at to get the engine healthy again?

jimnh20 wrote:

jimnh20 wrote: I currently have 180 gear legs with Pponk attachments Cleveland wheels, double-puck brakes, and 8X6 tires and a Scott tail wheel. Although the tail wheel assembly has been rebuilt and the alignment of the main gear has been adjusted, landing and roll-out is a serious adventure - not at all as stable as a stock 170.

n2582d wrote:[Jim, I thought of your recent post when I ran across this NTSB report which is about an accident of a C-170 with gear modifications similar to yours. Any of you Alaska guys have further details into this accident?

Thanks Gary - Doesn't make me feel a lot better about the mods, but gives me some hints about adjustments.

Jim

The NTSB ...MISSES THE BOAT...on many of their investigations. True,...they are very thorough and usually correct...but they demonstrate a serious lack of understanding of many lightplane accidents. (Remember the 172 which they claimed was lost (fatally for the pilot) when they claimed the IPC showed the O-ring on the wrong side of the check-ball which they claimed shut off the fuel? ...when in-fact...such improper assembly would PREVENT shutting off the fuel. When I contacted the NTSB chief investigator in-charge of that accident...She was completely disinterested in correcting her report! Instead, she wanted me to appeal to Cessna to issue an AD NOTE against all 100-series airplanes with that fuel selector valve! She did NOT want anyone to question her wrongful investigation and she adamantly refused to revisit it with me or anyone else.)

THIS particular accident investigation by NTSB also MISSES the mark! Their assumption of the "correct" tailwheel geometry is completely WRONG....as is their denouncement of the "L-19" tailwheel landing gear bracket, which they imply is incorrect for this model aircraft...when IN FACT it is THE CORRECTLY MODIFIED bracket, and the one which SUPERCEDES the previous steel "box" bracket which that investigator wrongfully thought should have been installed. (I guess he/she must have seen an earlier serial 170 at some point and made a final judgement based upon that observation without actually investigating the approved configurations for the aircraft.

In the most recent fatal accident involving our own beloved Members, the NTSB was apparently unaware of the hazards of full flap slips performed in B-models until our Prez pointed it out. Point being: It is heavily dependent upon the particular investigators personal experience and they often know very little of these aircraft. I now refuse to have blind faith in NTSB investigations of light plane accidents, and feel they should avail themselves of the type clubs when they investigate such accidents.

So....disregard the NTSB comments claiming expertise in landing gear configuration in the accident link provided in this thread. It is WRONG.

gahorn wrote:In the most recent fatal accident involving our own beloved Members, the NTSB was apparently unaware of the hazards of full flap slips performed in B-models until our Prez pointed it out. Point being: It is heavily dependent upon the particular investigators personal experience and they often know very little of these aircraft. I now refuse to have blind faith in NTSB investigations of light plane accidents, and feel they should avail themselves of the type clubs when they investigate such accidents.

George you have this story wrong. First I never talked to the NTSB. I had a chance contact with people who might be in communication with the FAA investigators. And after hearing this accident was looking strongly like a stall spin accident I asked this contact if it was at all possible to make sure the investigators understood the full flap elevator stall of the B model so that they could factor that in to the investigation. Subsequently I did talk personally to the lead FAA investigator who was reaching out to our type club and contacted me. We discussed the elevator stall, that it was real, and it fit this particular accident all to well. He was very pro type club and understood we are the people who know these airplanes best and are also one of the best sources to spread the word to owners about hidden dangers. He wanted to insure we got the word out which I assured him we would at the right time when some finding were released. I can not say whether he knew or did not know about the elevator stall prior to my involvement.

As for the NTSB, yes I am familiar with one of their findings which never mentioned the primary cause. A friend had an in flight fire at take off in a Balanca Super Viking. By all accounts he did a miraculous job flying his smoke filled aircraft in a tight low 360 back to the runway he left. As he rolled out, in consideration of the airlines who also use the runway, my friend consciously steered his aircraft off the runway into the grass were fire fighters put out the fire. The incident was witnessed apparently by an FAA investigator who happened to be there. His first question to my friend was is his ELT battery current. The NTSB report read "pilot lost directional control on landing". No mention anywhere on the official NTSB report of the fire.

So yes, like the TV and printed news I see in general, I look at NTSB reports understanding they could be very wrong.

I apologize, I did think it was NTSB who contacted you... sorry for the mis-recall.
I imagine the FAA inspectors who look at accidents make their reports, and any lack of understanding on their part likely influences NTSB.... The end-result is still heavily influenced by reports of folks not alway sufficiently knowlegeable to guide the investigation to the correct conclusion. Historically, NTSB has missed the mark more than we should be comfortable with small aircraft, was my point. Certainly, the NTSB report regarding the Alaska accident referenced above is quite wrong.

Meanwhile back at the ranch..................

We're doing exploratory surgery via borescope and pulling #5 cylinder on the C-145. The exhaust valve is leaking and assuming the inside of the engine doesn't look like it went through a blender and they're no chunks in the oil filter, valve repairs will commence and I will also address the mags, wiring harness, etc. to get the power plant back in commission.

THEN I'll get back to the gear issues

Who knows - in time I might even get to fly it again . However, patience is not one of my virtues, if any exist; so I expect to report back soon on how the engine fixes go soon.

Jim