Go Back  PPRuNe Forums > Flight Deck Forums > Tech Log
Reload this Page >

Engine Damage Turbo Prop.

Tech Log The very best in practical technical discussion on the web

Engine Damage Turbo Prop.

Old 23rd Oct 2013, 08:41
  #1 (permalink)  
Thread Starter
 
Join Date: Jan 2007
Location: Djakarta
Age: 31
Posts: 77
Engine Damage Turbo Prop.

Could somebody please enlighten me what engine indications one receives if a turbo prop like a PT6 suffers severe engine damage.

Thanks
arrow28 is offline  
Old 23rd Oct 2013, 09:58
  #2 (permalink)  
 
Join Date: Jan 2008
Location: Reading, UK
Posts: 10,684
N1 winding down ?
DaveReidUK is online now  
Old 23rd Oct 2013, 10:26
  #3 (permalink)  
 
Join Date: Jul 2013
Location: equatorial side of the Polar Jet
Posts: 194
NH~zero.This means the HP turbine has ceased and therefore engine has ceised. Also you will observe erratic indications on other instruments..and possibly some noise and vibration during seizure.There will almost certainly be High ITTs, dropping torque(or over torque during seizure befomage) and hardly any windmilling of the prop.Oily smell might seep through the aircon system and accompanying smoke.But the one most reliable indication in the cockpit is low to zero NH.

Last edited by Trackdiamond; 23rd Oct 2013 at 11:55.
Trackdiamond is offline  
Old 23rd Oct 2013, 10:27
  #4 (permalink)  
 
Join Date: Oct 2007
Location: Eastbourne
Age: 81
Posts: 54
Angry

Lots of nasty noises/vibration? Oil pressure dropping?
Four Turbo is offline  
Old 23rd Oct 2013, 10:43
  #5 (permalink)  
 
Join Date: Jan 2008
Location: All at sea
Posts: 1,702
A smooth run-down could be fuel leak, fuel control, fuel starvation or possibly ice ingestion, flying in very heavy precipitation, prolonged negative 'g'. None of which could be considered 'severe damage'. Whether one should attempt a relight in such a situation is a moot point. Personally I don't like the idea of relighting engines because they are not supposed to run down, but if a worse emergency could develop from not attempting a relight, why not have a go? Or if you did something silly like run a tank dry, of course you would relight and hope no-one noticed.

Severe damage suggests something broken, blades, bearings, near total loss of oil or perhaps an over-temperature due to mis-handling or fuel control problem. Bird strike will do it, and FOD is another possible culprit if on the ground - though the PT-6 and similar designs are fairly resistant to birds and FOD. Lightning strikes have been known to cause considerable damage to PT-6 engines in particular.

Indications of severe damage could include vibration, high TGT/ITT/TIT/EGT, possibly very high oil temperature, possibly the smell of oil or smoke through the air conditioning, a fire warning indication. Slow rotation of the power turbine accompanied by high temperatures is very bad news and of course no rotation of any section that is supposed to be rotating means it is seized and very, very dead. Or you are flying too slowly and about to become very, very dead.

Don't fall into the trap of mis-diagnosing low oil pressure as a failure in itself when it is often simply a result of the engine having already run down. Turbines will run for some time on hardly any oil pressure, provided that some oil is still in the system.
Obviously a relight must NOT be attempted if any of these indications are present.

Last edited by Mach E Avelli; 23rd Oct 2013 at 10:51.
Mach E Avelli is offline  
Old 23rd Oct 2013, 14:56
  #6 (permalink)  
 
Join Date: Jan 2006
Location: US
Posts: 2,057
BANG, followed by sharp metallic sounds as shrapnel exits the exhaust and hits the side of the fuselage, followed by yaw and power loss?
misd-agin is offline  
Old 25th Oct 2013, 17:35
  #7 (permalink)  
 
Join Date: Jan 2003
Location: The Heart
Posts: 812
A big bang and a big cloud of white smoke was the first thing that caught my attention when the aircraft I was flying suffered severe damage to its PT6.

The power lever was also stuck and the prop began causing considerable drag which made the climb performance suffer somewhat, it being a single engined aircraft.

Then I noticed the rpm to be zero and the ITT falling so I was sure something had ahappened.

On the other hoof, the fuel flow was zero so I was sure this would not be the limiting factor in dealing with the situation.
Miserlou is offline  
Old 25th Oct 2013, 21:55
  #8 (permalink)  
 
Join Date: Mar 2012
Location: On the couch
Age: 29
Posts: 19
Maybe a bit in a different direction than as posted above, but a broken prop drive shaft could also be considered severe engine damage. Meaning the engine runs perfectly fine, though no propulsion. Normal ITT and Nh, but no Tq
rayfill is offline  
Old 26th Oct 2013, 00:42
  #9 (permalink)  
 
Join Date: Mar 2008
Location: Western USA
Posts: 556
Mach E Avelli

Don't fall into the trap of mis-diagnosing low oil pressure as a failure in itself when it is often simply a result of the engine having already run down. Turbines will run for some time on hardly any oil pressure, provided that some oil is still in the system.
Obviously a relight must NOT be attempted if any of these indications are present.
True, but in the case of the mentioned PT6, the prop will feather with a loss of engine oil pressure.

When at a previous company we had a PT6 on a Twin Otter go from about 10-15# of torque to seizure in the blink of an eye. Thankfully it wasn't during the climb when at 40# of torque.
Desert185 is offline  

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Thread Tools
Search this Thread

Contact Us Archive Advertising Cookie Policy Privacy Statement Terms of Service

Copyright 2018 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.