A few anomalies with today's flight

Websterpilot

Well-Known Member
During a flight today, the Cutlass I was flying presented several issues that made me a bit concerned. Just curious to see if anyone may have experienced anything similar.

First: vibration in the rudder pedals up at cruise. Nothing major, but substantial enough to make me concerned. I've never felt that before. Changing power (different combinations of MP and RPM) and mixture settings made little difference. All engine instruments normal.

Second: Several minutes of +-100 RPM fluctuations (MP remained stable,) but stabilized without further incidence. Seemed to be unrelated to the other issues. Again never seen this before.

Third: Some type of fluid (possibly hydraulic fluid, couldn't tell from color or smell) running down the front of the firewall within the cockpit. Can't imagine how engine oil could get in there, so I'm assuming it's hydraulic oil from the master brake cylinder or lines?

To top it off, this was a return trip from the FSDO after my CFI checkride! So, I'm done with this Cutlass since I passed, but It's been bothering me since I got back on the ground. Let the mechanic know, but he looked at me like I had three heads.

Anyway, any ideas?
 

fholbert

Mod's - Please don't edit my posts!
Some oil and fuel pressure gauges have a wet line going into the cockpit. Sometimes they leak.
 

Der_Meister

Well-Known Member
The tach variation without power/sound changes is simply a tach error. It's on it's way to the grave. Fly freight and you'll learn to fly with out both of your tachs.
I love when the tach cables break, it makes flying such a guessing game.
 

Websterpilot

Well-Known Member
Thanks for the input folks! Meister, unfortunately I left my lunch in the fridge like an idiot, so I ruled out that possibility. Thanks for the laugh though, helps the brain come down off overdrive! What is POI? Wasn't sure if that was supposed to be PIO :p
 

Der_Meister

Well-Known Member
Thanks for the input folks! Meister, unfortunately I left my lunch in the fridge like an idiot, so I ruled out that possibility. Thanks for the laugh though, helps the brain come down off overdrive! What is POI? Wasn't sure if that was supposed to be PIO :p
Yea it was suppose to be PIO, but a POI (Principal Operations Inspector) is a scary FAA person who deals with 141 schools...lol
 

Websterpilot

Well-Known Member
Let's hope I'm done with the scary FAA people for a while. Nothing like sitting across the conference room table with an Inspector for over an hour while he goes through the logs page by page saying "hmmmm, okay that's strange... 1986...." Really man, it's 2012! Sheesh
 

Der_Meister

Well-Known Member
Let's hope I'm done with the scary FAA people for a while. Nothing like sitting across the conference room table with an Inspector for over an hour while he goes through the logs page by page saying "hmmmm, okay that's strange... 1986...." Really man, it's 2012! Sheesh
My initial ride ended up being 16hrs long. Failed the first day because I didn't say the rudder turned the airplane....
 

TwoTwoLeft

o- - - - - - -l
During a flight today, the Cutlass I was flying presented several issues that made me a bit concerned. Just curious to see if anyone may have experienced anything similar.

First: vibration in the rudder pedals up at cruise. Nothing major, but substantial enough to make me concerned. I've never felt that before. Changing power (different combinations of MP and RPM) and mixture settings made little difference. All engine instruments normal.

Second: Several minutes of +-100 RPM fluctuations (MP remained stable,) but stabilized without further incidence. Seemed to be unrelated to the other issues. Again never seen this before.

Third: Some type of fluid (possibly hydraulic fluid, couldn't tell from color or smell) running down the front of the firewall within the cockpit. Can't imagine how engine oil could get in there, so I'm assuming it's hydraulic oil from the master brake cylinder or lines?

To top it off, this was a return trip from the FSDO after my CFI checkride! So, I'm done with this Cutlass since I passed, but It's been bothering me since I got back on the ground. Let the mechanic know, but he looked at me like I had three heads.

Anyway, any ideas?
1) Did you remember to close the cowlflaps?
2)Tach cable probably needs some lube
3) What fholbert said....
You survived. Good job, now go get some students!
Failed the first day because I didn't say the rudder turned the airplane....
Say WHAT?:aghast:
 

rframe

pǝʇɹǝʌuı
The oil pressure lines in Cessna's are often a literal hard pressure line running to the gauge, these were originally aluminum tubing and it stress cracks from vibration over time. Also, if someone wasn't careful with routing controls they will easily wear through over time where anything rubs on them. When they fail they can go from a small leak to a pretty major gush quickly. Best to have them replaced with rubber tubing if there's any hint of fatigue or chafing. I experienced it myself with one that gave out during ground operations, it dumped about 1/8th quart in a few minutes of taxi...not something you'd want to have happen in flight if at all preventable :)
 

Der_Meister

Well-Known Member
You failed for not giving a wrong answer?
Yep, he flew challengers for 4 years previous years. So I can understand him thinking that the rudder turned the airplane. I spent about 30-45 explaining how turns work. In the end he said I didn't explain how the rudder worked in combination with the ailerons enough but I spent like 15 on adverse yaw and what the rudder did; so I figured it was just him trying to get his fail ratio up. The flight was 1.2 and the simplest flight ever.
 

Websterpilot

Well-Known Member
I had the cowl flaps closed 3/4 of the way.

That makes sense about being a leak in a pressure line. Good to know. I just assumed airplanes use electrical sending units installed in the block itself, similar to a car. Makes you wonder why you wouldn't get fluctuation on the gauge at the same time during a leak?
 

TwoTwoLeft

o- - - - - - -l
I had the cowl flaps closed 3/4 of the way.

That makes sense about being a leak in a pressure line. Good to know. I just assumed airplanes use electrical sending units installed in the block itself, similar to a car. Makes you wonder why you wouldn't get fluctuation on the gauge at the same time during a leak?
Good thing he didnt ask you about that stuff on the checkride! :p Before you file that in the "nice-to-know" box... You can see why it's important to know how instruments get their information. Just being aware could prepare you for oil/fuel in the cockpit or explain the sudden "loss" of oil pressure when the electrical system failed...

I've had oil pressure gauges weep oil before. As long as there is constant pressure (no air in the line) going to the gauge there won't be any fluctuation. It'll just make a mess over time. With a BIG leak there will be a loss of pressure indicated at the gauge.
 

TwoTwoLeft

o- - - - - - -l
I love when the tach cables break, it makes flying such a guessing game.
Cover up the Tach and fly the plane. The only time you should need to look at the tach is if you trying to get a quantitative value to set your fuel burn. Everything else should be by sound. If you know the airplane well enough, (keeping altitude in mind, below 3K, below 10K, or above 10K) know what your IAS should be for cruise. Go full throttle, and reduce it to where you can maintain your desired airspeed with out losing altitude. Then go do some pattern work. This is a great exercise to do with your students.

If its a constant speed prop. You can always take a sharpie and mark where 2500 RPM and your cruise setting is on the prop control. Or just guess, check & learn while you have the luxury of a tach to do so.
 

mshunter

Well-Known Member
It's a Cutlas, with ump-teen million hours of "learning" on it likely. It's going to do crap like that, just like an old car. It's fine, just keep flying it.
 
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