Analogue v Digital

If either type fail, they are as useful as each other and have equal placing in the human factors department!

SASless, correction graciously and gratefully accepted. :ok:

Display faults: an age old problem, as Sid so correctly points out. Will be interested to see what further the AAIB can sort out.

if redundancy systems fail, or their information is not transferred correctly, means being not received at the receiving end, it seems minor mistakes can end up with what happened. As the AAIB report has been very carefully worded, they may have already more information which is not appropriate to broadcast now in public. So if there was an issue with transferring information, caution warnings, alerts at some stage..at what stage have the pump switches been put into the incorrect position?


There are (at least 2) different sorts of Swiss cheese: one with few big bubbles, they are obvious, but then there is an other one too.

Wild guess here, and smack me if I am being dim.

If one engine quit, mayhap a restart was on his mind for that engine while the other was still running?

Again, wild guess.

Oh gawd! Not the Swiss cheese! I've enjoyed being in cheese free zone :uhoh:

How often are the tank contents checked against the fuel used on previous sorties,,,? Is there a suitable Dipstick available/provided/locally produced...?
Is there a `flowmeter`page available in the system ? or is that another option ?

some smell here is quite strong. maybe its just old and not Swiss.

SilsoeSid
Accepted that a faulty display can be useless, analogue or digital. There was a fault code recorded for the display but it is unknown from the AAIB report as to what effect this would have on the information available to the pilot.

Given that the crew were all equipped with night vision goggles, it is possible that there are ergonomic issues switching between using the goggles and unaided vision. I assume that the display brightness needs to be manually adjusted down quite a bit to avoid dazzle when using night vision goggles. If the googles are removed and the display brightness is left at very low level, then perhaps this could be an explaination for not noticing the developing fuel situation?

The AAIB report is quite specific in stating that there is no evidence of impact damage while the helicopter was airborne, the fuel system should have allowed free flow of fuel had the supply tanks been full, there were no anomalous chips or metal particles on the chip detectors, and that all damage found was consistent with a high deceleration impact.

So we are left with two switches in the wrong position and some sort of display fault that may or may not have affected the flight display panel. Everything else can be attributed to the engines flaming out sequentially.

At the point the second engine failed, it should have been possible to carry out an autorotation. This clearly didn't happen, so we are left with human factors and cockpit ergonomics as probable causes.

Sid - a fault within a black box such as the display system does not necessarily mean that it fails to function. The reporting is simply of maintenance issues which will at some time require attention. Whilst it is possible that a fault report could indicate a complete melt-down, it is far more likely that there was some very minor malfunction requiring routine attention. A conversation with your crewmen will tell you more about this. I have worked in the design team for similar items.

On another topic, do you find that the fuel sensors play up more during late autumn, and when a warm front is followed by a cold night?

Crunching Numbers presents chart of switches, post 2192
 

All too easy to toggle the wrong switch on a panel like that. Horrifying.
Are these four identical switches the ones incorrectly set? It rang alarm bells for Lonewolf 50 in his long post number 2304. Also Art of Flight in post 2323 calls for a redesign of the switch panel. Gouli in two posts, 2388 and 2402 also deplores a panel arrangement of "identical switches all in a line"

Whether or not the accident is blamed on the switches, somebody had better get busy and redesign that panel! The sense of touch remains when it is difficult to see, or to hear. Make some longer, fatter, curved, whatever it takes to make them distinct from each other.

I hope the AAIB would make such a recommendation.

Another question arises; the posts say goggles for night vision may make it harder to read the panels. Do chopper pilots wear gloves?

Put the Pump switches back down on the console where they were in the 105/117's....where you can see the things.

Better yet....just turn them on and leave them on.

In my memory....I do not recall ever having a Transfer Pump fail on a 105/117. How many fail on the 135/145 series?

Better question yet.....are they the same pumps....on all four aircraft?

Completely agree Sid... It seems to me the same non helicopter pilots ask a specific 135 technical question, are given an answer, ignore the answer then ask the same crap over and over... :ugh:

Pump switches again...

Yes, all 4 look the same but when you switch on a prime pump PRIME PUMP comes up on the CAD. When you switch off an XFER pump F PUMP FWD/AFT comes up on the CAD, even I can tell the difference... (as I can read English, just about) and despite earlier suppositions, pilots do tend to look at, and read any amber cautions on the CAD. Therefore, what could cause a switch mix up to go unnoticed, a CAD fault perhaps??? If not a CAD fault then perhaps the prime pumps were on for a reason!

Out of interest, from an earlier discussion, do any 135 pilots here routinely fly with the prime pumps on all the time? I don't know of anyone who does.

Silsoe,

You have brought the discussion back to highlight the key point from the report - this ongoing investigation into issues with the displays.

An awful lot of dancing around the big elephant in the room.

If you have a mind to fly close to the endurance limit it might be worth making sure you know how the fuel system works, what the lights mean and what the switches all do.

Flying on with RED low fuel lights is madness.

How often are EC135 pilots flying into these low fuel states??

OK, lets put some perspective on this.

This vid shows what you are presented with as soon as you switch on the Prime Pumps.
In addition to the Master Caution light in front of the pilot, you get the CAD cautions of PRIME PUMP, the flashing bars and the audio.
(please ignore the warning lights as the ac was shutdown)

http://i52.photobucket.com/albums/g1...psjslqbhva.jpg

This is a snapshot taken from the TFO's viewpoint.
You can see the Master Caution light, the CAD indications of the PRIME PUMP cautions, the bars, and they will also get the audio.

http://i52.photobucket.com/albums/g1...psl6u3e1nb.jpg

Finally for this post, this is the CAD after the PRIME PUMP caution has been acknowledged.
This is what the CAD would normally be indicating in the situation of;
Transfer Pumps off and Prime Pumps on.

http://i52.photobucket.com/albums/g1...psriekebiw.jpg


As you can see, there's a lot going on that has to be 'ignored' by each member of the crew.
Still convinced that all was indicating as it should?

Having read the report, it is clear that 76 KGS was remaining in the main tank and both supply tanks were effectively empty.

This situation is entirely commensurate with the finding that both transfer pumps were switched off.

The LOW FUEL warnings generated by the thermistors in the supply tanks and recorded by the VMS also support the first two findings.

Safety needs to be assured and it is clear to me that this helicopter fuel system was not operated correctly to the point that the systems gave more than adequate warning of impending doom. In addition the pilot operated below the published MLA and, at face value, appears unaware that his airmanship would have led him to carefully manage his fuel, based on his airborne time, if he had a full and complete understanding of his fuel system.

The EC135 has a long and faithful service record in HEMS and Police roles. I see nothing in the AAIB report that in any way tarnishes that record.

Flight Safety principles demand that we accept the most probable causes unearthed during AAIB investigations. Flailing around tryin to grasp at straws in an effort to avoid the bleeding obvious serves no man. It is misleading, unhelpful and deflects the necessary attention that all emergency service pilots should pay to their fuel management towards the end of a long task.

I did not know this pilot but I do know that none of us are immune from such circumstances that he found himself in that night.

The remaining fuel never made it to the engines cos the pumps needed to make it happen we're selected OFF. The pilot had a few more chances to get it right and switch them back on again as the warning lights began to illuminate. Finally a chance to survive if the correct response to double OEI is deployed. SID I know this is deeply unpalatable to you but I think you should breath out and face the facts and findings detailed in the AAIB report and see them for what they actually represent.

Human beings use five senses to assess what's going on. Sight, sound, smell, taste, and touch.

Sight (displays, warnings, red lights, etc) Sound (alarms, bells, engine making funny noises or worse, no noise at all). Smell (if you smell smoke you really have a problem). Taste? (nausea can overwhelm everything else)

And last, but not least, when all else fails, touch. I fly much better without gloves on, and reach without looking for the trim, the airbrake lever, the stick, etc. I have read on previous posts that the controls in helicopters have been differentiated in texture to avoid confusion.

Can anyone tell me please, do helicopter pilots wear gloves?

I'd say way too much amber text for a normal situation. With the pump switches set correctly for cruise, there'd be only the green pitot msg, right?

Is what you are getting at, that the only explanation would be total failure of the CAD, e.g. black screen, because noone in his right mind would have ignored/continued flying with that much yellow in the CAD?

DB - what exactly were the circumstances? Has the Pilot and crew really ignored all warnings - if they were visible to them? I just wish to understand a bit more if there could have been 'understandable' - not looking for 'acceptable' - reasons for such a handling of the situation. As I know from own mistakes and 'bad days' there often is. I learn best from understanding a situation and not just being told 'right' or 'wrong'. Fuel taken out of the heli was not significantly below MLA, heliport was some 1:30 minutes away. Did the pilot know the exact kg's in the tank - if CAD was working which is a big ?; so according his calcs he might have landed just at the margin - on a day with absolutely no weather restrictions.
I didn't 'know' the Pilot but I met him very briefly as a real person in real life. To know a bit more and get to understand a possible reason for the events and how they relate to this tragic outcome makes this so unreal event with a real person (not only one!) a lot more digestable for me. Same may apply for others? Some people like close relatives could stay sort of paralysed for life if they don't get real answers to what has happened. Big thank you to Sid and Art from my side.

Well said DB.