Rental Pilots work on planes

brien23

brien23

Cleared for Takeoff
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May 31, 2005
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Display name:
Brien
It's been over a year since pilots are doing things to the FBO rental aircraft that they think is right. Someone pulled the vent tube on a C-172 behind the strut down into the slip stream and thought it should be that way? One would think the paint line on the tube would be a clue that it might be wrong but did it anyway. This and bent trim tabs and other things pilots do that they feel is the right, is this a problem of the CFI's not instructing pilots not to do that or just pilots that justify what they are doing.
 
Morons.

That one word explains so much in the world. :D
 
There’s more than a slight chance that a lot of CFIs don’t know that the fuel vent is supposed to be behind the strut, nor about ground-adjustable trim tabs.
 
brien23 said:
It's been over a year since pilots are doing things to the FBO rental aircraft that they think is right. Someone pulled the vent tube on a C-172 behind the strut down into the slip stream and thought it should be that way? One would think the paint line on the tube would be a clue that it might be wrong but did it anyway. This and bent trim tabs and other things pilots do that they feel is the right, is this a problem of the CFI's not instructing pilots not to do that or just pilots that justify what they are doing.
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Yah, and this isn't the worst of it though. Some schools (not all) trade time with students to do things like change engines, instruments etc. with only a little general mechanical aptitude, no formal training not to mention no certification. I once new a school owner that did the schools engine overhauls. His credentials were he was an auto mechanic and had a friend with an a&p who would come by and do a little pencil wiping on the log books probably after the fact. Be careful what you rent.
 
Dave Palacios said:
Yah, and this isn't the worst of it though. Some schools (not all) trade time with students to do things like change engines, instruments etc. with only a little general mechanical aptitude, no formal training not to mention no certification. I once new a school owner that did the schools engine overhauls. His credentials were he was an auto mechanic and had a friend with an a&p who would come by and do a little pencil wiping on the log books probably after the fact. Be careful what you rent.
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I think a lot of CFIs may not know what is kosher or not kosher.
 
Dave Palacios said:
I think a lot of CFIs may not know what is kosher or not kosher.
Click to expand...

Yes and the sad truth is many of these CFI's have only a few more hours than the student they are struggling to teach. After 25 hours training I bought a 182 to finishing my training and had 20 hours in it when I had to switch CFI's to finish. So 60 hour student doing mock check rides. The kid borrowed MY 182 to get his high performance endorsement. An hour later he starts yelling at me in panic because I adjusted manifold pressure before RPM.
 
NordicDave said:
Yes and the sad truth is many of these CFI's have only a few more hours than the student they are struggling to teach. After 25 hours training I bought a 182 to finishing my training and had 20 hours in it when I had to switch CFI's to finish. So 60 hour student doing mock check rides. The kid borrowed MY 182 to get his high performance endorsement. An hour later he starts yelling at me in panic because I adjusted manifold pressure before RPM.
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You may or may not be aware of his concerns, he may not have understood the reason why its not a good idea only the fact that he was cautioned against it. You didn't say which way you went but i will guess, increase throttle first before advancing the prop (reducing prop pitch). If it happened once and awhile probably wouldn't cause a catastrophic failure. The concerne is it can detune the counter weights, suddenly applying a heavy load on the engine. However there is an oracle with a name thats some kind of shrub, that says "rubbish, it won't hurt it". It's your plane, so its up to you how you operate your engine. Recently there was an engine that lost a pin holding the weight. theory is that a snap ring was incorrectly installed.
 
The Tech that signs off on the tasks has a responsibility to oversee progress.

I; for one, would be a proponent of using FaceTime or Skype for some.

That = Not ALL.
 
Dave Palacios said:
You may or may not be aware of his concerns, he may not have understood the reason why its not a good idea only the fact that he was cautioned against it. You didn't say which way you went but i will guess, increase throttle first before advancing the prop (reducing prop pitch). If it happened once and awhile probably wouldn't cause a catastrophic failure. The concerne is it can detune the counter weights, suddenly applying a heavy load on the engine. However there is an oracle with a name thats some kind of shrub, that says "rubbish, it won't hurt it". It's your plane, so its up to you how you operate your engine. Recently there was an engine that lost a pin holding the weight. theory is that a snap ring was incorrectly installed.
Click to expand...

Dave that's hokem that's been disproved over and again. The engine operation manual from Continental say the engine can be safely operated up to 4 inches over square. This CFI has exactly 40 minutes experience with a prop governor.
 
NordicDave said:
Dave that's hokem that's been disproved over and again. The engine operation manual from Continental say the engine can be safely operated up to 4 inches over square. This CFI has exactly 40 minutes experience with a prop governor.
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Hokem ? Lol, well i don't have a tcm op manual so i have to take your word for it, don't a poh in front of me but prety sure afm people say that. but if harm comes (at least right a way) then what the heck go for it. Just curious have you seen inside engine, particularly crank / counter balance ?
 
Thread Drift but I’ll say one size does not fit ALL.

Key is to operate the particular engine within the operating limits

as defined by the manufacturer.

It’s not as simple as only one factor either.

BMEP or cylinder pressure is a concern with some.

Super/turbo charged engines can be more susceptible and

can suffer from detonation .

Again; operate per Manual.
 
Dave Palacios said:
You didn't say which way you went but i will guess, increase throttle first before advancing the prop (reducing prop pitch). If it happened once and awhile probably wouldn't cause a catastrophic failure. The concerne is it can detune the counter weights, suddenly applying a heavy load on the engine.
Click to expand...
Improper MP/RPM sequence detuning the counterweights? That's the first time I've heard that, and I'm a retired aircraft mechanic, commercial pilot and flight instructor.

No, the concern is detonation. Too much cylinder pressure at lower RPM can cause detonation and serious engine damage, sometimes catastrophic. Often the pilot will have a habit of doing this incorrectly, and get away with it for some time, but minor damage, repeatedly, adds up until something fails.

Follow the POH and avoid settings outside the recommendations, however brief it might be.

Too many pilots now have never driven a car with a manual-shift transmission. If you're approaching a steep hill, do you just hold the throttle down until the RPM falls of and then change to a lower gear? No. You get the RPM up first, then add throttle. Otherwise you are stressing that engine, even if the knock sensors retard the time to prevent detonation. The bearings don't appreciate high loads at low RPM.
 
Magman said:
The Tech that signs off on the tasks has a responsibility to oversee progress.

I; for one, would be a proponent of using FaceTime or Skype for some.

That = Not ALL.
Click to expand...
I don't know your background, but i will assume you are an ap by your handle (magman). i am not sure the word is "oversee" i think it is "supervise" but oversee works for me at least. As far as face time etc. not sure that's legal. I won't kick back & forth regs, but i think most fisdos would have a dim view of it, at least in the past, today not so sure. i think if ASIs aren't working from home they probably don't want to leave the office. after an inspection i squawked an item, the owner said he would order the part (elevator bearing). I assumed he would call me to install it, instead he text me a picture of the assembled elevator. It seems he got a friend to install it and figured with a picture i would sign it off ! (obviously his friend was not a mechanic or he would have signed it off) the owner is a long time flight instructor, i was shocked but laughed about it and asked him if i stood in front of an airplane and had a picture taken and text it to him if he would sign me off for a bfr ? He went silent. As i get older it gets tempting but then i think " if it took 40 hours to get a mechanics cert, there would be a ton of mechanics. No offence but doing business that way seems lazy and greedy. Needless to say but i didn't sign off work that i didn't at least supervise in person. i am not an attorney but that seems like it would be fraud. Again no offence intended.
 
Regs and their interpretation do change.

Notice my comment was “ Not ALL”.

When overseeing fabric work I feel no need to do in person observation

or the direction the dope is being stirred.

With Flight Controls , engine work etc it’s a different tune.

The phones can be extremely helpful in diagnosis.

If “ a picture is worth a thousand words “ than live

interactive video is worth 50x that.

Repetitive needless trips can really be frustrating for all involved.

If I were to charge 5 hours for changing a Brackett Filter Element on

a c-150 the whole internet would know what a bad guy I am!

Encouraging folks to fly a sick airplane to a more convenient

location is not good at all.
 
I remember on my very first pre-flight, standing there looking at the rudder trim tab bent to the side.

The CFI saw me, chuckled and said "Don't even think about it"
 
Magman said:
Regs and their interpretation do change.
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They do. But it has to start somewhere. Since this appears to be an important topic to you perhaps start the process?
The 1st link is the FAA site on how to initiate a rule change. It provides links to the underlying USC law and how to start the process.
The 2nd link below is from Part 11 and it shows you how to fill out your request.
As they say if you plant the seed...

https://www.faa.gov/regulations_policies/rulemaking/petition
1717439666352.png
https://www.ecfr.gov/current/title-...bject-group-ECFR55878f43afde57a/section-11.71
1717439749000.png
 
Dave Palacios said:
The concerne is it can detune the counter weights,
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the weights are just a mass of metal. How do they become altered?? The springs are wear items, but they are pretty robust and won't simply wear out after 1 slight misuse
 
pfarber said:
the weights are just a mass of metal. How do they become altered?? The springs are wear items, but they are pretty robust and won't simply wear out after 1 slight misuse
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There are no springs. Lyc O-540

1717457423798.png
1717457469074.png

O-360:

1717457546662.png
1717457581622.png

Continental O-470:

1717457698726.png
1717457740703.png



TSIO-520:
1717457840013.png
1717457883511.png

IO-550 doesn't have any springs either.

In what engine did you see springs as part of the dynamic counterweight assembly?
 
Dan Thomas said:
Most dangerous thing in the world, according to some mechanics: A pilot with a screwdriver.
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Heck, I always thought that equaled job security....
Maybe I should have loaned them my screwdriver more often??? ;)
 
Dave Palacios said:
Hokem ? Lol, well i don't have a tcm op manual so i have to take your word for it, don't a poh in front of me but prety sure afm people say that. but if harm comes (at least right a way) then what the heck go for it. Just curious have you seen inside engine, particularly crank / counter balance ?
Click to expand...
Hmm, ever look at the MP and RPM on a sea level take off? 29 - 30 inches and 2500 - 2700 RPM,

Hmm, how about turbo engines? Mine is 13 inches over square at take off (39", 2600 RPM).
 
Piston Engines are all the same. Just different!

Many engines limiting MAP restrictions.

Most are Maximum but some have a Minimum during descent.

R-2000 was one. 2700 RPM and 50 MAP for Max Power.

Btw- The term “ Take-Off Power” was never used on this aircraft as it

implied Taking the Power Off!

Following established Operating Procedures to include terminology

iIs the best way to have good results with a large operator. Ie USAF.
 
Magman said:
The Tech that signs off on the tasks has a responsibility to oversee progress.

I; for one, would be a proponent of using FaceTime or Skype for some.

That = Not ALL.
Click to expand...
It's a slippery slope
 
Magman said:
Regs and their interpretation do change.

Notice my comment was “ Not ALL”.

When overseeing fabric work I feel no need to do in person observation

or the direction the dope is being stirred.

With Flight Controls , engine work etc it’s a different tune.

The phones can be extremely helpful in diagnosis.

If “ a picture is worth a thousand words “ than live

interactive video is worth 50x that.

Repetitive needless trips can really be frustrating for all involved.

If I were to charge 5 hours for changing a Brackett Filter Element on

a c-150 the whole internet would know what a bad guy I am!

Encouraging folks to fly a sick airplane to a more convenient

location is not good at all.
Click to expand...
It's a slippery slope !
 
In some areas Light Aircraft A &P’s are in short supply.

Yet some folks seem to think that the Tech should just “ eat” the time

and costs involved in getting to a small job.

My belief is the members of EAA & AOPA should be the moving force

in incorporating technology.

Thanks to Bell for the refs but I’ll probably start with discussing with the

Friendly FSDO Folks for their take. Pushing for a Rule Change at my age

( I think Charles Taylor was one of my students) would be jousting with

windmills for others benefit.
 
Dave Palacios said:
Recently there was an engine that lost a pin holding the weight. theory is that a snap ring was incorrectly installed.
Click to expand...
https://drs.faa.gov/browse/excelExternalWindow/FR-ADFRAWD-2023-05339-0000000000.0001
NordicDave said:
Dave that's hokem that's been disproved over and again. The engine operation manual from Continental say the engine can be safely operated up to 4 inches over square.
Click to expand...
All one has to do is study the stupid POH. For the 182Q which has a Continental O-470:

1717521683669.png

And...

1717521715168.png


And...
1717521908070.png

That is one of six pages of cruise charts for that airplane.

I am constantly amazed at the questions and debates on this forum that would not even be an issue if pilots knew their POHs. Even those without an airplane can get POHs like this online for free.
 
@Dan Thomas The POH for the 182 is one of many valid engine settings. Those cruise numbers are not the only viable numbers, which were written in a different ERA influenced heavily by lawyers and marketing people.

You're a mechanic. Read any Lycoming or Continental engine operating manual to see the full range of factory operating parameters for a particular engine series.

Mike Busch has more than one good reference videos which might help:

Screenshot 2024-06-04 at 11.24.43 PM.png
 
NordicDave said:
@Dan Thomas The POH for the 182 is one of many valid engine settings. Those cruise numbers are not the only viable numbers, which were written in a different ERA influenced heavily by lawyers and marketing people.

You're a mechanic. Read any Lycoming or Continental engine operating manual to see the full range of factory operating parameters for a particular engine series.

Mike Busch has more than one good reference videos which might help:

View attachment 129566
Click to expand...
Here's a chart from an IO-470 manual. The 182's POH I quoted was based on the O-470-U.

1717603859941.png

This is the sea-level performance cruise chart. At a max cruise of 2450, the recommended MP limit is a hair over 24". At a cruise RPM of 2100, the recommended max MP is about 23.4". I don't see any suggestion there of running the engine 4" oversquare.

https://www.csobeech.com/files/TCM-IO470-Operation-Manual.pdf

See if you can find in that manual any 4" oversquare numbers. Or find a manual that does. It might indeed exist.
 
Take off and climb.

Full throttle and max RPM is about 4" over square.
 
Yes. Right
Pinecone said:
Take off and climb.

Full throttle and max RPM is about 4" over square.
Click to expand...
At or near sea level. But this is a cruise chart. In the takeoff and climb the mixture is richer for better cooling and detonation margin.
 
Anybody can make an aircraft unairworthy.
 
Dan Thomas said:
Yes. Right

At or near sea level. But this is a cruise chart. In the takeoff and climb the mixture is richer for better cooling and detonation margin.
Click to expand...
The point was that Continental allows operation at 4" oversquare.
 
Dan Thomas said:
See if you can find in that manual any 4" oversquare numbers. Or find a manual that does. It might indeed exist.
Click to expand...
Done. We usually cruise at 33" and 2500 RPM for 75% power.PowerSettingArrow.jpg
 
Yes, turbocharged engines run much higher MPs, but turbocharged engines are not usually normally-aspirated engines with a turbo stuck onto them. They are built differently to take the higher pressures. An exception is the occasional turbonormalized engine, where the turbo maintains the MP at sea level pressure.

Lycoming mentions that bearing sizes are larger in their turboed engines.

Then there's the cost and TBO differences. https://generalaviationnews.com/2020/02/23/turbo-vs-naturally-aspirated-engines/

It reflects more than just the cost of the turbo.
 
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