Police helicopter crashes onto Glasgow pub

[SilsoeSid]

UK police aviation has developed rapidly in the last 20 years (and declined in the last 2)...

Careful AoF, at the next 'get together' identities will be sought and answers will be openly given, just like the last one

[mbriscoe]

The air ambulance is mainly operated during daylight hours to call outs, though transfers take place during the hours of darkness (mainly SAR territory), so the 'net' of fuel stops at night in Scotland will not have developed much if at all beyond the airfields that have regular profit making hours.

The RAF/RN/CG helicopters have their own fuel supplies around the Highlands located at some of their regular landing sites. They are 'self-service'.

[codeen]

I beg your pardon but,

I would have rather read these headlines in the news:

Police helicopter emergency lands after engines stopped producing power. All persons on board and on the ground are safe.

Engine power is not required to control a helicopter in flight, rotor RPM IS. Therefore, the loss of engine power could be a symptom of loss of fuel but not loss of rotor RPM. Control of the rotor is partially in the collective pitch system as you know i`m sure.

[Lonewolf_50]

Codeen, not sure how much of this thread you have taken the time to read.
It does take a bit of weeding to get to the good stuff, and the non repetitive stuff. This thread spawned detailed discussion about EC-135 and its fuel system (in the EC-135 thread) and a passionate discussion about autorotation, loss of power in singles and twins, low and high inertia heads, and much else related to controlling NR and flying the bird to the ground successfully when one is unpowered.

Links here:

EC-135 thread

The "Entering Autos" Discussion

Our friend heli may be suggesting you take a look at what has already been presented for consideration.

[Back at NH]

The whole thing doesn't sit right with me.

The facts of the matter would indicate that the pilot ignored low fuel warnings, and was caught out by the subsequent rundown of both engines.

There are 2 aspects of concern for me.

1. There still remains a gap in any knowledge of what to this helicopter between engine rundown and arrival through the roof.

2. I simply cannot believe that an experienced pilot could sit there and watch his fuel run out without taking any action. It is beyond comprehension that a low fuel warning can illuminate and that he would not check the gauges and observe the supply tanks emptying with fuel still in the main tank and not do anything about it. Why were the transfer pumps not turned on when the low fuel warnings came on? I simply don't buy it, sorry. Then this situation continues until he sees 0/76/0 and both engines quit, and this causes such a surprise that there appears to be no attempt to enter autorotation. We are expected to believe that after, what - 20 minutes of warning, he wasn't expecting and couldn't react to the rundown of the engines?

I don't doubt the events as published by the AAIB in any way, but how do they compare to the reality as seen in that cockpit on that night. Something isn't right. There's more to this than meets the eye.

[DrinkGirls]

Back at NH and many others out there. The AAIB has given you your answers in coded form. Some have tried to tell you, but the trivia talkers have overtalked them. The answers have been given. A pilot DIDNT sit and watch his supply tanks empty.
I may have misread the report, so apologise in advance if i missed a reference.

I appear to read that ONE particular caption is not mentioned on the list, the amber........

FUEL

There is only one scenario where that caption doesnt illuminate and the two red warnings do come on. That is the recent fault with supply tanks showing permanent full. If the amber fuel DID illuminate, i am totally wrong of course...........
Dave may have been presented with a 46/75/44 indication with two red lights?????????

[Scuffers]

That's not what it said or implied.

[Art of flight]

Anyone who really thinks they found the elusive nugget of a clue as to how this happened, beyond the fuel situation, and need to share it with us really should have a read through some of the previous 118 pages before expecting new answers to old questions.

[SilsoeSid]

A couple or six questions.

1.For the engineers.
What is the function of and the criteria for the cautions F QTY DEGR & F QTY FAIL ?

2. For the 135 pilots.
If the CAD was to fail, where would you expect to see the fuel quantity displayed?
If the F QTY FAIL caution appeared, what would you base your remaining flight time on?
What cautions are lost with a loss of the CAD?

3. For all pilots
Would you necessarily report an instrument failure to ATC if you didn't think it worthy of a PAN/Mayday call?

4. For non pilots/casual observers.
You are driving from Edinburgh to London for a meeting, a distance of 405 miles (M6), and at the start of your journey your car computer says that you have a range of 450 miles. As your journey progresses, the fuel consumption remains consistant with the initial computer output;
If your fuel gauge and computers range output failed at Milton Keynes, would you continue your trip to the meeting in London?

[Reely340]

1.For the engineers.
What is the function of and the criteria for the cautions F QTY DEGR & F QTY FAIL ?

You mean besides:http://www.pprune.org/rotorheads/529...ml#post8210003

Code:

These tests have shown - when water is entering the space between the two concentric metal tubes of the probe - it will decrease the output signal (frequency) of the probe. In case of a high concentration of water, the frequency can decrease to such a level that the CAD recognizes the probe as failed – showing either an F QTY DEGR or F QTY FAIL caution on the CAD. Also there is a potential risk that the CAD shows a higher fuel quantity level compared to the actual fuel level within the fuel tank system.

Just a software engineer, but a proficient googler :
For EC145 I've found something on 3 - 19 and 3 -20 of
http://helicopterindia.com/yahoo_sit....241202201.pdf

Code:

F QTY DEGR
(MISC)
Conditions/Indications:  Failure of one main tank sensor.
Procedure: Set pitch attitude between –3° and +8° before reading the approx. available fuel 
quantity, then calculate remaining flight endurance.
CAUTION
THE DEGRADED FUEL QUANTITY INDICATION REPRESENTS THE
MINIMUM FUEL LEVEL WITHIN PITCH ATTITUDE RANGES OF –3° TO +8°

Code:

F QTY FAIL
Conditions/Indications: Failure of the fuel quantity indication system.
CAUTION
THE FUEL QUANTITY INDICATION SYSTEM HAS FAILED. 
DO NOT CALCULATE FLIGHT ENDURANCE USING THE FUEL QUANTITY INDICATION.

ACCURATE FUEL QUANTITY INFORMATION IS ONLY PROVIDED BY
THE LOW FUEL WARNING LIGHT ACCOMPANIED BY WARNING GONG.
Procedure: LAND AS SOON AS PRACTICABLE

edit: same thing on EC135 P2+ http://helicopterindia.com/yahoo_sit...2.24193407.pdf
Pages 3 -26, 3 - 27

Code:

F QTY DEGR
(MISC)
Conditions/Indications: Failure of one main tank sensor.
CAUTION
THE DEGRADED FUEL QUANTITY INDICA TION REPRESENTS THE 
MINIMUM FUEL LEVEL WITHIN PITCH ATTITUDE RANGES OF –3° TO +6°

Procedure: Set pitch attitude between 0°and +/–1° before reading fuel quantity,
then calculate remaining flight endurance in accordance with that “degraded”
fuel quantity indication.
NOTE In this attitude for endurance calculations conservative fuel quantity is displayed.

F QTY FAIL
Conditions/Indications: Failure of the fuel quantity indication system.
CAUTION
THE FUEL QUANTITY INDICATION SYSTEM HAS FAILED. 
DO NOT CALCULATE FLIGHT ENDURANCE ACCORDING THE FUEL QUANTITY INDICATION.
 FUEL QUANTITY INFORMATION ONLY BY LOW FUEL WARNING LIGHT ON THE WARNING PANEL AND BY GONG.

Procedure:LAND AS SOON AS PRACTICABLE

[Reely340]

3. For all pilots
Would you necessarily report an instrument failure to ATC if you didn't think it worthy of a PAN/Mayday call?

Naah. What should an ATC do with that information?
I'm the PIC, if I'd been really concerned I'd call a PAN and request a straight in approach. But I'm just a fresh PPL, what do I know..

[Fortyodd2]

DrinkGirls,

"..........presented with a 46/75/44 indication with two red lights?????????"

I can accept that as a possible scenario and would explain why the Amber Fuel caption did not appear - what I cannot understand is why flight was continued instead of landing and why the Prime pumps were on and the Tx pumps off.

[catch21]

IF I was driving an expensive company car with the graphics "Very Important Bankers" on the side, carrying two people from another company that were also going about their business, and I had to return the vehicle with a minimum level of fuel to do 75 miles, I'd have to decide whether I wanted an ear-roasting for returning with below minimum required fuel level or an ear-roasting for parking up in a hostile environment with consequent risk to the vehicle, inconvenience to the people I was carrying and having to wait a considerable time for the RAC to tip up and refuel me. I think I'd press on.

With no minimum fuel requirement I'd definitely press on. With a faulty gauge that told me I'd both get there and be above the minimum there is no question.

[catch21]

If one supply tank sensor was faulty, reporting let's say a full supply tank when it was nearly empty, what might the display 46/75/0 be diagnosed as? Leaking supply tank?

As you can't select which tank the pumps feed, would you not turn the transfer pumps off as a precaution to prevent any more loss, and then be prepared to fly and land with the single engine remaining and its 46kg?

Also, it would not be a surprise when the first engine flamed out indeed you would be expecting it.

[rantanplane]

But I'm just a fresh PPL, what do I know..


not that much, so you might not trust anything! and probably land immediately if possible. and will be safe as no wrong assumptions. Sometimes experience can be a death trap.


regarding fuel consumption, if there was a fault in the supply tank gauges (both??) and they remained constantly full on the display (as they should do until usable fuel is taken out of main tank), main tank fuel should decrease according normal in flight fuel consumption. With main tank pump switches OFF there is NO change in fuel level in the main tank.


The pilot could think ALL gauges and/or the CAD or something else in the fuel calc system doesn't work at all. So perhaps ignore the CAD / FMS info and simply continue flying a la clock. (can the CAD be switched off?)


Is that a possible scenario (which Silsoe is just asking us here to understand?) or am I as stupid as me dog. (I still fly with b&w analogue instruments and like them for some reason)

[Art of flight]

IMHO, an excellent series of posts on this page, Sid has asked questions he knows the answers to and others are starting to contribute by responding to those questions. It really does start to paint a picture of a complicated situation that Dave might have been faced with.

Those that think he just sat there doing nothing should read these recent posts.

[Scuffers]

Originally Posted by catch21

If one supply tank sensor was faulty, reporting let's say a full supply tank when it was nearly empty, what might the display 46/75/0 be diagnosed as? Leaking tank?

As you can't select which tank the pumps feed, would you not turn the transfer pumps off as a precaution to prevent any more loss, and then be prepared to fly and land with the single engine remaining and its 46kg?

Also, it would not be a surprise when the first engine flamed out indeed you would be expecting it.

if you had that big a leak, would you not be aware of it?, also the supply tank would be reducing at a steady rate (as the engine burns it) that should be familiar to the pilot?

all that aside, if I belives I had a major fuel leak and was going to be on one engine anytime soon, I would chicken out pretty fast, call mayday and put it down ASAP.

this is not the same as a car running out of gas....

[catch21]

if you had that big a leak, would you not be aware of it?, also the supply tank would be reducing at a steady rate (as the engine burns it) that should be familiar to the pilot?

When everything is normal the supply tanks stay full until the main tank is depleted. As the main tank may have been indicating 75kg, one might easily assume the abnormal condition is diagnosed as a supply tank level falling rather than the other supply tank level remaining where it should be.

all that aside, if I belives I had a major fuel leak and was going to be on one engine anytime soon, I would chicken out pretty fast, call mayday and put it down ASAP.

The fuel system is compartmentalised to cope with this situation. It might go back to Sid's question, with an apparent 46kg of usuable fuel and minutes from base, why would you land a serviceable aircraft?

If, from the indications you have in the cockpit, you diagnose a fuel system fault, i.e. a leaking supply tank, you wouldn't be too worried about an ear-roasting for landing below minimum fuel, presumably?

[catch21]

The recent AAIB report shows intermittent Low Fuel warnings on one tank, and a permanent Low Fuel warning on the other.

So, the two low fuel sensors are behaving differently to some extent. Is this "normal"? If not, which behaviour is "normal", several intermittents or one permanent?

[Edited to add: I guess this isn't a condition you would normally get into in flight and ground testing would give a different behaviour anyway.]

[henry_crun]

Originally Posted by catch21

what might the display 46/75/0 be diagnosed as?

If I were an alert and aware pilot (which I'm none of) I would diagnose this as an overindication because I know jolly well I have much less than 100kg remaining. That dam' display's playing up again. Why won't they listen?

But I remember switching on the transfer pumps, so I'm probably ok....possibly ok......no, let's get this thing down on the ground soonest.