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-   -   Police helicopter crashes onto Glasgow pub (https://www.pprune.org/rotorheads/528850-police-helicopter-crashes-onto-glasgow-pub.html)

ShyTorque 29th Dec 2013 19:14

I used to have the CP "graph" ingrained in my brain. More difficult if you'd previously flown the aircraft with the original "draggy" metal blades, because the CP limits changed.

27 degrees nose up was the only recommended EOL flare profile back then. No need for such radical moves with the plastic blades fitted, much more forgiving, rather like a big Gazelle.

Sorry for further thread drift! :O

Shawn Coyle 29th Dec 2013 20:17

Just slightly off topic (but probably relevant somewhere).
How do you react to (FADEC Engine):
Overtorque and Low Rotor RPM simultaneously - which both go away when level lowered, but return when lever raised.
Further indications:
#1 engine - N1 pegged, N2 zero, torque zero, TOT pegged, oil indications normal.
#2 engine - N1 appropriate for torque, N2 100%, TOT appropriate for torque.
No engine failure declared...
What happened? What do you do next?

SilsoeSid 29th Dec 2013 23:18

Is there a trick meaning for 'pegged'?

This is all very much like an episode of QI. Everyone thinks they know the answer, but fear to give the obvious answer because it's bound to be followed by sirens.


ShyTorque 30th Dec 2013 00:21

Pegged is a term that needs clarification.

What are the other indications? You didn't post like for like. Is the N2 meant to be at 100%, or was it selected to something else? The last two types I've flown have selectable N2 for takeoff/landing, eg 107 or 102%.

[email protected] 30th Dec 2013 06:25

Looks like a frozen No1 engine due to a N2 sensor failure.

Shawn Coyle 30th Dec 2013 13:14

Sorry for the confusion. 'Pegged' in this instance means at maximum 30" power limits.

Shawn Coyle 30th Dec 2013 13:15

All sensors are duplicated.

ShyTorque 30th Dec 2013 13:42

Then you appear to be describing a #1 engine drive failure of some sort.

10Watt 30th Dec 2013 21:15

The other aircraft are operating normally.

The cause is known. The public are paying for everything.

What gives these servants of the public the right to hide facts ?

Shawn Coyle 30th Dec 2013 23:06

Before I reveal the cause - pause for a moment and consider two things.
1) The pilot would have never seen or guessed that you could have simultaneously an overtorque warning and a low rotor RPM warning. Not in the flight manual, and never discussed in any training.
2) What action do you take with those symptoms?

jayteeto 31st Dec 2013 07:05

10watt. That is a serious accusation. You say the cause of the accident is known, where did you get that information from. As an EC135 pilot, I would like to know the cause, but the last I heard, they hadn't got an answer??????????

Fortyodd2 31st Dec 2013 07:45

10Watt,
They have the "Right" because theirs is the responsibility to produce a report that is 100% factually accurate including all of the factors that lead up to the moment of impact regardless of how far back they have to trawl. If that is not good enough for you then I suggest you lend them your clearly superior crystal ball.
Like JT2, I also have a vested interest in knowing the causes and events leading up to the crash but I have confidence in the AAIB that if there is anything I need to know then I will be told.

Non-PC Plod 31st Dec 2013 08:34

Shawn,

Symptoms you describe look like power turbine seizure. If there is zero N2 and no torque, then it appears that the back end of the engine isnt turning. (Although the gas gen is going at max to try to maintain 100% power turbine speed) Most important thing is always the Nr - once that is sorted out by lowering the lever as necessary, and the aircraft is climbing, careful diagnosis will reveal which engine is providing torque and which isnt - shut down the bad one!

Shawn Coyle 31st Dec 2013 09:23

Non-PC Plod:
Nearly right.

SilsoeSid 31st Dec 2013 10:02

I think a fair few posts ago most of us had a good idea of what we were going to do, but smelt a ..... "

... You didn't want to do that, coming on!

Harry Enfield - Didn't want to do it like that!

cattletruck 31st Dec 2013 10:07


an overtorque warning and a low rotor RPM warning
On singles this is indicative of over pitching the blades. The remedy is to simply lower the collective.

Now on twins it seems to be quite a gotcha, I can think of many interpretations of what this event could mean, but I have very little twin experience so I won't postulate my thoughts.

PieChaser 31st Dec 2013 10:52

So you are in the hover with 70 litres unusable in the main tank, transfer pumps off. Both supply tanks are full so you have about 20 mins flight time remaining.
Number one engine quits, number two spools up to compensate but is now using more fuel. How long have you got now?
The fuel in supply tank one is redundant (about 40 litres I think)
Only two options.
Option one land.
Option two requires a bit more cunning, anyone want to respond?

Tandemrotor 31st Dec 2013 10:57


When the US Army first got their UH-60s (& eventually AH-64s) there were too many cases of having one engine fail and then shutting off the remaining good engine.
Not infallible, (Kegworth) however, involving two pilots when taking non-reversible actions in vital systems is normally considered advantageous.

Just saying.:rolleyes:

SilsoeSid 31st Dec 2013 11:17


So you are in the hover with 70 litres unusable in the main tank, transfer pumps off. Both supply tanks are full so you have about 20 mins flight time remaining.
Number one engine quits, number two spools up to compensate but is now using more fuel. How long have you got now?
The fuel in supply tank one is redundant (about 40 litres I think)
Only two options.
Option one land.
Option two requires a bit more cunning, anyone want to respond?
I think the clue here is, 'Number one engine quits'!

This begs the obvious question of ... If one engine has quit, why are you still wanting to remain hovering for as long as you can?

SilsoeSid 31st Dec 2013 11:21

Tr, perhaps the problem is understood more easily by reading Art of Flights earlier posts from around the 28th ….


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