Police helicopter crashes onto Glasgow pub

[Arrab]

G0ULI

what if he though he had full supply tanks. Then he would not have been deliberately planning to land below min fuel.

Why would he think the supply tanks were full?

Well that's exactly the kind of false indication being seen in EC135s right now duel to faulty fuel sensors.

[mickjoebill]

Is it rare in helicopters of any type for up to 15% of fuel to be unusable if pumps are not working?

Based on comments here, should pilots be more aware of the difference between useable fuel under normal ops compared to when pumps are not operating?
In the case of the EC 135 apparently it is 1.5% versus 15%.
The entire safety margin if flying by the clock!

I can't find any reference in flight manuals to unusable fuel with pumps off.

A case of the manufacturers and industry relying too much on the electronic cockpit?


Mickjoebill

[G0ULI]

Arrab
A reasonable question. The crucial point arrives when a pilot intentionally continues flight in the knowledge that the aircraft will land with below minimum fuel reserves.

You kind of need a good excuse for that.

Faulty fuel guages could be considered a valid reason, or it may be that the flight must continue for safety reasons to avoid hostile terrain, weather, etc.

In this case, SilsoeSid has posted some very informative pictures that suggest that the pilot was perhaps flying with no fuel information due to a display fault.

It wasn't lack of fuel that was the problem, it just wasn't getting through to the engines. There was sufficient fuel overall to continue flight to the destination and land safely despite the fact that fuel minimums would have been breached. It was reasonable to continue the flight to base given the circumstances.

[MightyGem]

NPAS are subject to commercial pressures to keep the aircraft in the air for as long as possible

No they are not. NPAS are not in the world of making money. More like saving money. That's why I could always decide when it was time to RTB for weather/fuel, or decide not to go flying because of weather, and not expect to be questioned about it.

[henry_crun]

SilsoeSid has posted some very interesting information about an ongoing 20kg transfer of fuel after the transfer switches are turned off. Whatever the reason for this quirk of the fuel management system, it might cause a pilot to see fuel flowing and convince him that the transfer switches are on when they are not.

May I suggest that the fuel indications over Dalkeith might have been as follows:

Arrive over Dalkeith with fuel display indicating 47/99/43.
After one minute of task receive and heed transfer pump caution 47/96/43.
Continue task for a further two minutes 47/90/43.
Start to fly back to base, nvg on, check fuel: no cautions, 47/86/43.
Continue flight back to base, no cautions, 47/80/43.
All's well, fuel flowing ok, dark below, so turn lighting down for best nvg vision.

At 47/76/43, unknown to pilot, the supply tanks begin to deplete.

The fuel indications all look good, but it is the run-on 20kg he is seeing. Indicates that the transfer pumps are on and working although they are still switched off.

henry_crun
only a 'white-coated boffin'

[rotorspeed]

SS - Your response concerns me - you say I got my facts wrong. You say the red low fuel light comes on at 48kg remaining. The manufacturer says 60kg, according to Airbus Helicopters' information as posted earlier. They also say then you must land in 8-10 minutes. Given that, I would take the lesser time of 8 minutes as the limit, but I'm surprised you want to take the longer end of the at 10 minutes. Maybe I have misunderstood something, but perhaps you could review these "facts" and set out what they really are?

Anyway, it seems that you have agreed that you would not actually land when you had just 70kg in my example, which was the original point.

Thanks for all your EC135 fuel indications info btw, it has been very helpful!

[SilsoeSid]

Morning Rotorspeed;

SS - Your response concerns me - you say I got my facts wrong. (a) You say the red low fuel light comes on at 48kg remaining. The manufacturer says 60kg, according to Airbus Helicopters' information as posted earlier. (b) They also say then you must land in 8-10 minutes. Given that, I would take the lesser time of 8 minutes as the limit, but I'm surprised you want to take the longer end of the at 10 minutes. Maybe I have misunderstood something, but perhaps you could review these "facts" and set out what they really are?

my brackets


(a)
Lets have a look at the facts for the this one, which was in reference to your posting, "You also know your red low fuel warning light has not yet come on, which it should at 60kg,"

ref: http://www.airbushelicopters.com/sit...18-Rev0-EN.pdf

"LOW FUEL 1 Illuminated - 26 - 34 kgs
LOW FUEL 2 Illuminated - 22 - 30 kgs "
(The serviceable range is 48 - 64 kgs)

Therefore at 48 kgs, both Red Warnings should be on, not as you say at 60 kgs.

(b)
This is in reference to your posting, "when the book says you must land within another 8 minutes."

ref:
http://helicopterindia.com/yahoo_sit...2.24193407.pdf
http://www.airbushelicopters.com/sit...19-REV0-EN.pdf

LOW FUEL 1 and/or LOW FUEL 2
"LAND WITHIN 10 MINUTES" (a committed to memory item)

Therefore when the light(s) come on you must land within 10 minutes, not 8.
It does not say 8-10 minutes, it says 10. You are mixing up different types

Anyway, it seems that you have agreed that you would not actually land when you had just 70kg in my example, which was the original point.

No I haven't. I gave you my example.
Given the choice between landing 10 kgs below 70 kgs in order to get to Blackpool airport, having to write a report and explain what happened … and ditching... I think I'd take the former ….. wouldn't you?

[SilsoeSid]

Rotorspeed,

I have no problems answering your questions as best I can, complete with the relevant links to factual information and reference, however would you please give the courtesy of answering the questions I have put to you instead of ignoring them and continuing to what seems like simply 'having a go' at me for some reason.

Thanks.

[SilsoeSid]

mickjoebill;

I can't find any reference in flight manuals to unusable fuel with pumps off.

Perhaps clicking on this will help

First result, pages 85 & 86

[FlightSpanner]

A post by Brilliant Stuff on the EC135 threat told us that during testing for the ASB one aircraft drained the main tanks to an indicated 12Kg (Xfer pumps off) before the supply tanks started to drop, as all 135 tanks are built the same surely this shows that the main tank indicating system can under read, the ASB highlights issues with the supply tanks over reading.

What I'm saying is it can't be ruled out that he was seeing 47/12/43, knowing he was close to his min landing fuel he would have been planning to return to base, possibly during the last task, this fuel qty would also not be to far off what he expected to have then the reds start showing up, still with the same 47/12/43 indications.

Trying to figure out what is going on, why the Reds are on, then one engine quits, I can understand why the primes may have been accidentally switched on, that's a huge workload to deal with.

As said many times previously, he had enough fuel just not in the right place, and maybe he was being shown it was!

Thoughts?

FS

[Pittsextra]

Whilst we spin our wheels over what fuel level might be reasonable or not I'm not sure what is ambiguous about :-

The red “low fuel” warningis triggered when there are 32 kilograms of fuel in supply tank 1 and 28 kilograms of fuel in supply tank 2. When this occurs, the pilot has 8-10 minutes left to land, regardless of the conditions and as dictated in the flight manual.
As previously stated, the red “low fuel” warning is generated by an independent indication system with separate sensors in each supply tank. This warning continues to operate correctly even if the fuel gauging is inaccurate.

So regardless of a fault with pumps or operator error in not turning things on / off it seems pretty clear that if you get the red "low fuel" alarm you need to land.

he had enough fuel just not in the right place, and maybe he was being shown it was!

Thoughts?

Even if the fuel gauge suggests you have fuel in the tank it seems a dumb trade to believe one instrument over another and allow yourself to be more optimistic. In fact it doesn't "seem" it was.

[SilsoeSid]

Whilst we spin our wheels over what fuel level might be reasonable or not I'm not sure what is ambiguous about :-

Pitts, it's nice when quoting from a few pages back to give us a link or reference.

You are referring to your post 2545 http://www.pprune.org/rotorheads/528...ml#post8341322 that links to the Airbus Helicopters FAQ's on the 135.

What you must appreciate is that this is a general FAQ page for the 135 range.

The statement you quoted that you support so strongly of ...

"The red “low fuel” warning is triggered when there are 32 kilograms of fuel in supply tank 1 and 28 kilograms of fuel in supply tank 2. When this occurs, the pilot has 8-10 minutes left to land, regardless of the conditions and as dictated in the flight manual."

… is totally generic as the low fuel warnings can come on as low as 26 & 22 respectively as opposed to your quoted 32 & 28.
For SPAU the 10 minutes would apply, not 8 minutes, as would be dictated in its flight manual.

So, to answer your question, the information you gave us is ambiguous in that it applies to the whole range of the 135 series and not to the specific airframe involved

[Pittsextra]

Hey SS - I am quite prepared to believe your knowledge of the EC135 type is greater than mine. That said you don't seem to fundamentally disagree with my overall point.

That being when the red "low fuel" warning alarms you have this 8-10 min window which as you point out is dependant upon the specific model.

As the AAIB report suggests

the No 1 supply tank (left) contained 0.4 kg of fuel and the No 2 supply tank

(right) was empty.

Are you suggesting he didn't have his 10 minutes?

Apologies for the missing ref; I'm simply using the information Eurocopter themselves give here

[Art of flight]

"So regardless of a fault with pumps or operator error in not turning things on / off it seems pretty clear that if you get the red "low fuel" alarm you need to land."

Yes you do need to land - within 10 MINUTES, not 8....read the correct instructions for the correct aircraft!

And a minor point, it's not an alarm......it's a Warning. Continued loose terms just encourages others to think there's more to the system than there actually is.

[Pittsextra]

Whats the difference between an alarm and a warning?

http://http://www.oxforddictionaries.../alarm?q=alarm

As for the 8-10 min time frame that we are getting a hard on about, we hope that the pilot likely knew that difference. and as the AAIB report 0.4kg in one and zero in the other supply tank is it not as likely he flew for the appropriate amount of time with this red "low fuel" warning?

Given EC135's in general are still flying I think that maybe the case.

[SilsoeSid]

Pitts;

Even if the fuel gauge suggests you have fuel in the tank it seems a dumb trade to believe one instrument over another and allow yourself to be more optimistic.

I'll let you find the fault in that statement yourself

[SilsoeSid]

Pitts;
Hey SS - I am quite prepared to believe your knowledge of the EC135 type is greater than mine. That said you don't seem to fundamentally disagree with my overall point.

That being when the red "low fuel" warning alarms you have this 8-10 min window which as you point out is dependant upon the specific model.

No, it's not a matter of anyones greater knowledge, just the ability to read the frequently referred and linked to flight manual relevant to the type.

I do disagree with you, there isn't an 8-10 minute window, it clearly states "Land Within 10 minutes"

Pitts;
Whats the difference between an alarm and a warning?

From the already linked to flight manual for the EC135;

A red warning light indicates a hazard which may require immediate corrective action.
A yellow caution indicates the possible need for future corrective action.


I think the more relevant publication is the Flight Manual and not an online Oxford dictionary to which your link doesn't even work

[Pittsextra]

I'll let you find the fault in that statement yourself

It would be at fault had it not ended with "and allow yourself to be more optimistic"

Anyway we can wish it wasn't so, can talk it around, analyse individual words and try to find the escape.

The Warning Unit has provided information on the order in which warnings were triggered

during the flight but not when they occurred. The unit recorded the normal warnings associated with starting the helicopter, followed by a warning free status. It subsequently recorded intermittent LOW FUEL 1 warnings for the left fuel supply tank, then a permanent
LOW FUEL 2 warning for the right fuel supply tank. This was followed by a further temporary LOW FUEL 1 warning, before it became permanent for the remainder of the flight. These LOW FUEL warnings are triggered by thermal sensors in the supply tanks. For this helicopter build configuration, they indicate when there is approximately 32 kg and 28 kg of fuel remaining in the left and right supply tanks, respectively. On receipt of these warnings, the manufacturer’s flight manual for the helicopter instructs the pilot to ‘LAND WITHIN 10 MINUTES’.

I suggest he didn't heed that warning.

[SilsoeSid]

Optimistic, as in if you have 2 differing indications of fuel you believe the higher value?

What planet are you on?

[Pittsextra]

SS you're crazy. Alarm/Warning for me in my head that term meant the same thing i.e. it draws you to an action. I'm not trying to educate the world when I said it I was merely writing as I thought. Although even as you link/ cut, paste and attach a variety of things I'm not sure how you come to a different conclusion if you use the word alarm around the Red "low fuel" warning.

8mins or 10 mins what is your point?? Lets be clear. Either you are familiar with the flight manual and you fly 10mins or you perhaps choose a more conservative value if you are not. Flying for 8 mins when you have fuel for 10mins won't end in a heap. Flying for 10mins when you have fuel for 10 mins just might.