Tucker1
Topic Author
Posts: 38
Joined: Sat Mar 17, 2018 6:04 pm

Private pilot training question.

Fri Jun 08, 2018 1:49 pm

Last evening I was out in my driveway and as far as I could tell there was a c172 flying about 2,000 feet overhead. Just as I was watching it, there was a loud "pop" from the engine then no sound as I watched it sail behind other houses. My question is if during training the instructor will stall the engine as a test for the trainee? If so, wouldn't that be too low for that test? I did hop in my truck to try and follow it and where I thought it would go down if indeed needed. Found nothing, haven't heard anything.
 
kengo
Posts: 219
Joined: Mon Apr 08, 2013 11:04 am

Re: Private pilot training question.

Fri Jun 08, 2018 3:18 pm

Sounds like a misfiring engine. It happens sometimes and when I was working towards my PPL, experienced a few pops myself. To your question, no, the instructor will not cutoff the engine purposely. In a simulated engine failure, the instructor throttles back the engine to idle.
 
Conniston
Posts: 8
Joined: Mon Dec 10, 2007 5:18 pm

Re: Private pilot training question.

Fri Jun 08, 2018 5:55 pm

Most likely practicing emergency procedures and the instructor simulating an engine failure by retarding the throttle to idle. The pop was from the throttle being closed too quickly, resulting in unburned fuel detonating in the exhaust.

In aviation we avoid using the word "stall" is reserved for the aerodynamic phenomenon, it's not used in any relation to the power plant to avoid confusion. But to answer your question, the engine is never shut down on purpose for training, engine failures are simulated by retarding the power to idle.
 
Tucker1
Topic Author
Posts: 38
Joined: Sat Mar 17, 2018 6:04 pm

Re: Private pilot training question.

Fri Jun 08, 2018 6:09 pm

Yeah, I should have used a different term. Thanks guys! I pry wasn't close enough hear it throttle back up.
 
User avatar
Starlionblue
Posts: 18333
Joined: Fri Feb 27, 2004 9:54 pm

Re: Private pilot training question.

Sat Jun 09, 2018 1:16 am

Conniston wrote:
Most likely practicing emergency procedures and the instructor simulating an engine failure by retarding the throttle to idle. The pop was from the throttle being closed too quickly, resulting in unburned fuel detonating in the exhaust.

In aviation we avoid using the word "stall" is reserved for the aerodynamic phenomenon, it's not used in any relation to the power plant to avoid confusion. But to answer your question, the engine is never shut down on purpose for training, engine failures are simulated by retarding the power to idle.


The term "engine stall" is used in jet engines to describe a flow disruption.
"There are no stupid questions, but there are a lot of inquisitive idiots." - John Ringo
 
User avatar
fr8mech
Posts: 7118
Joined: Mon Sep 26, 2005 9:00 am

Re: Private pilot training question.

Sat Jun 09, 2018 1:34 am

Conniston wrote:
In aviation we avoid using the word "stall" is reserved for the aerodynamic phenomenon, it's not used in any relation to the power plant to avoid confusion.


Ummm, compressor stall in a jet engine?
When seconds count...the authorities are minutes away.
Unless it's expressly prohibited, it's allowed.
 
N766UA
Posts: 7984
Joined: Thu Jul 29, 1999 3:50 am

Re: Private pilot training question.

Sat Jun 09, 2018 9:00 pm

Starlionblue wrote:
Conniston wrote:
Most likely practicing emergency procedures and the instructor simulating an engine failure by retarding the throttle to idle. The pop was from the throttle being closed too quickly, resulting in unburned fuel detonating in the exhaust.

In aviation we avoid using the word "stall" is reserved for the aerodynamic phenomenon, it's not used in any relation to the power plant to avoid confusion. But to answer your question, the engine is never shut down on purpose for training, engine failures are simulated by retarding the power to idle.


The term "engine stall" is used in jet engines to describe a flow disruption.


No it isn’t. Compressor fan blades experience stalls; engines do not.
fr8mech wrote:
Conniston wrote:
In aviation we avoid using the word "stall" is reserved for the aerodynamic phenomenon, it's not used in any relation to the power plant to avoid confusion.


Ummm, compressor stall in a jet engine?

Not related to the operation of the engine. Again, the fan blade is stalling, in exactly the same way a wing stalls: airflow disruption. It’s purely aerodynamic.
 
User avatar
fr8mech
Posts: 7118
Joined: Mon Sep 26, 2005 9:00 am

Re: Private pilot training question.

Sat Jun 09, 2018 11:27 pm

Not related to the engine? Of course it is. When the fan or compressor stalls, or surges, you most certainly affect the operation of the engine, to include the very real possibility of a flameout.

So, yes, there word stall is used when we describe power plant faults on aircraft.
When seconds count...the authorities are minutes away.
Unless it's expressly prohibited, it's allowed.
 
N766UA
Posts: 7984
Joined: Thu Jul 29, 1999 3:50 am

Re: Private pilot training question.

Sun Jun 10, 2018 1:05 am

fr8mech wrote:
Not related to the engine? Of course it is. When the fan or compressor stalls, or surges, you most certainly affect the operation of the engine, to include the very real possibility of a flameout.

So, yes, there word stall is used when we describe power plant faults on aircraft.


That’s entirely misleading and inaccurate. The term “stall” is used to describe airflow disruptions that can have *effects* on turbine engines. You are describing the *symptoms* of a compressor stall; its effects (which are related, obviously). The actual *stall* is a disruption of airflow, in this case over a fan blade or blades, and the stall itself can happen regardless of the overall health of the engine. Therefore, the compressor stall and its root cause have nothing to do with the engine itself, and one would never refer to an engine fault that did not involve disrupted airflow as a “stall,” as that word is purely used to describe aerodynamics, not mechanical parts. Do you see what I’m saying here?
 
User avatar
fr8mech
Posts: 7118
Joined: Mon Sep 26, 2005 9:00 am

Re: Private pilot training question.

Sun Jun 10, 2018 1:30 pm

N766UA wrote:
That’s entirely misleading and inaccurate. The term “stall” is used to describe airflow disruptions that can have *effects* on turbine engines. You are describing the *symptoms* of a compressor stall; its effects (which are related, obviously). The actual *stall* is a disruption of airflow, in this case over a fan blade or blades, and the stall itself can happen regardless of the overall health of the engine. Therefore, the compressor stall and its root cause have nothing to do with the engine itself, and one would never refer to an engine fault that did not involve disrupted airflow as a “stall,” as that word is purely used to describe aerodynamics, not mechanical parts. Do you see what I’m saying here?


I see what you’re saying, and don’t really dispute the airflow bit, but, and you know there is a but, the overall health of the engine can cause a stall (of the airflow). Bleed valve (chapter 75) faults, variable stator vane faults, fuel control faults, the various linkages and controls that link all together can be worn. All those are part of the engine and the engine’s overall health can be affected by the components’ health.

Reciprocating engines do stall in the classic sense. And, I’ve never heard another term used to describe a recip that has unexpectedly shutdown, other than stall. If the engine stalls, then it’s an engine stall, if the aircraft stalls, then the aircraft has stalled. The word “stall” is used correctly in both case.

The op used the proper term with proper usage when he said “the instructor will stall the engine”.
When seconds count...the authorities are minutes away.
Unless it's expressly prohibited, it's allowed.
 
Conniston
Posts: 8
Joined: Mon Dec 10, 2007 5:18 pm

Re: Private pilot training question.

Mon Jun 11, 2018 2:24 am

fr8mech wrote:
N766UA wrote:
That’s entirely misleading and inaccurate. The term “stall” is used to describe airflow disruptions that can have *effects* on turbine engines. You are describing the *symptoms* of a compressor stall; its effects (which are related, obviously). The actual *stall* is a disruption of airflow, in this case over a fan blade or blades, and the stall itself can happen regardless of the overall health of the engine. Therefore, the compressor stall and its root cause have nothing to do with the engine itself, and one would never refer to an engine fault that did not involve disrupted airflow as a “stall,” as that word is purely used to describe aerodynamics, not mechanical parts. Do you see what I’m saying here?


I see what you’re saying, and don’t really dispute the airflow bit, but, and you know there is a but, the overall health of the engine can cause a stall (of the airflow). Bleed valve (chapter 75) faults, variable stator vane faults, fuel control faults, the various linkages and controls that link all together can be worn. All those are part of the engine and the engine’s overall health can be affected by the components’ health.

Reciprocating engines do stall in the classic sense. And, I’ve never heard another term used to describe a recip that has unexpectedly shutdown, other than stall. If the engine stalls, then it’s an engine stall, if the aircraft stalls, then the aircraft has stalled. The word “stall” is used correctly in both case.

The op used the proper term with proper usage when he said “the instructor will stall the engine”.


That's not correct. In aviation, the term "stall" is not used for describing an engine shutdown, regardless of whether is a piston or a turbine, to avoid confusion with the term stall used in aerodynamics.

I could have worded my earlier post better, as the blades on a jet engine compressor can indeed stall under certain conditions, and as such the word stall can be "related" to a jet engine (still in the aerodynamic sense, completely unrelated to the term stall used to signify engine stoppage)

However for the purpose of the OP's question, the main point is that the term engine stall as commonly used in automobiles is not applicable for aircraft, it has a completely different meaning.
 
User avatar
Starlionblue
Posts: 18333
Joined: Fri Feb 27, 2004 9:54 pm

Re: Private pilot training question.

Tue Jun 12, 2018 4:30 am

The term "Engine Stall" is used multiple times in the Airbus 330 FCOM I'm looking at right now. This includes an abnormal procedure for "ENG 1(2) STALL". "This alert triggers when an engine stall is detected."

If it's good enough for Airbus and Rolls-Royce.... ;)
"There are no stupid questions, but there are a lot of inquisitive idiots." - John Ringo
 
Karlsands
Posts: 6
Joined: Sat Sep 16, 2017 2:53 pm

Re: Private pilot training question.

Wed Jun 13, 2018 3:17 am

Misfiring like an older muscle car would, common in the 177, and in older 172s

Who is online

Users browsing this forum: No registered users and 5 guests

Popular Searches On Airliners.net

Top Photos of Last:   24 Hours  •  48 Hours  •  7 Days  •  30 Days  •  180 Days  •  365 Days  •  All Time

Military Aircraft Every type from fighters to helicopters from air forces around the globe

Classic Airliners Props and jets from the good old days

Flight Decks Views from inside the cockpit

Aircraft Cabins Passenger cabin shots showing seat arrangements as well as cargo aircraft interior

Cargo Aircraft Pictures of great freighter aircraft

Government Aircraft Aircraft flying government officials

Helicopters Our large helicopter section. Both military and civil versions

Blimps / Airships Everything from the Goodyear blimp to the Zeppelin

Night Photos Beautiful shots taken while the sun is below the horizon

Accidents Accident, incident and crash related photos

Air to Air Photos taken by airborne photographers of airborne aircraft

Special Paint Schemes Aircraft painted in beautiful and original liveries

Airport Overviews Airport overviews from the air or ground

Tails and Winglets Tail and Winglet closeups with beautiful airline logos