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EC135

Old 12th Jan 2014, 18:53
  #981 (permalink)  
 
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May respectfully suggest that all crew go on a FACTORY training course ensuring that they fully and correctly understand the systems they are operating.
Robin400 - I'm sure if I ask nicely my CP wont mind if I and the other 70 odd pilots nip over to Germany for a few days at the company's expense for a bit of fuel system training and sightseeing. God knows I could do with it this time of year...
BC
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Old 12th Jan 2014, 18:59
  #982 (permalink)  
 
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I have a cross-section view of the pump from my training notes. It looks to me like an impeller type pump.
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Old 12th Jan 2014, 18:59
  #983 (permalink)  
 
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I have asked how you manage the TRANSFER PUMPS to ensure that one is submerged in fuel with the change in pitch attitude with no reply.

My understanding is the one pump may be above the fuel and switched off.
Thats the procedure according FLM. A dry running fuelpump gives a CAUTION and has to be switched off. So when in hover atttitude, the FWD pump will be the first when the main tank is coming to around 60 kg. In cruise flight ( nose low ) it will be the AFT pump. You have to consider it, when transitioning to cruise after long hover flight and low fuel in main tank -> AFT pump off and FWD pump ON again!!!

skadi
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Old 12th Jan 2014, 19:03
  #984 (permalink)  
 
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I thought these are diaphragm not impeller pumps? I'm sure I read that and would seem to me to be the better choice with these low fuel flow rates.
What utter rubbish, any 135 pilot or engineer would know that they are centrifugal pumps and why they have to be so!
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Old 12th Jan 2014, 19:08
  #985 (permalink)  
 
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Robin400 - I'm sure if I ask nicely my CP wont mind if I and the other 70 odd pilots nip over to Germany for a few days at the company's expense for a bit of fuel system training and sightseeing. God knows I could do with it this time of year...

All part of the expense running a safe professional outfit.

Maybe the concern in Germany will pay the bill

Last edited by Robin400; 12th Jan 2014 at 20:13.
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Old 12th Jan 2014, 19:09
  #986 (permalink)  
 
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FFS, guys, why so confrontational?
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Old 12th Jan 2014, 19:30
  #987 (permalink)  
 
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My posts are not intended to be a slur on all pilots involved in the operation of the 135, if you feel that that is the case I apologise unreservedly. I accept that all the posts on here are not from 135 pilots.

From the posts on here I am left with a sense of unease regarding the level of understanding.
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Old 12th Jan 2014, 19:41
  #988 (permalink)  
 
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Thats the procedure according FLM. A dry running fuelpump gives a CAUTION and has to be switched off. So when in hover atttitude, the FWD pump will be the first when the main tank is coming to around 60 kg. In cruise flight ( nose low ) it will be the AFT pump. You have to consider it, when transitioning to cruise after long hover flight and low fuel in main tank -> AFT pump off and FWD pump ON again!!!

Skadi. Thank you very much. That is exactly as I imagined it would be.
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Old 12th Jan 2014, 20:14
  #989 (permalink)  
 
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All part of the expense running a safe professional outfit
Robin400 - Much as I would relish the opportunity, unfortunately commercial practicalities would never allow it...

There seems to be a lot of concern about pilot familiarity and understanding of the 135 fuel system on this thread from non 135 people. The system hasn't changed markedly from when I was taught about it 7 years ago and I am still happy with how it operates practically day to day as a pilot. I don't feel I need further training and as to all the minute design intricacies etc. I am happy to leave that to the engineers and boffins in white coats.

BC
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Old 12th Jan 2014, 21:49
  #990 (permalink)  
 
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10 pages of disagreements about how the fuel system works - uphill syphoning , swirl, pump types, CoG attitude changes, ltrs / kgs water in capacitive fuel senders, confusion about wether one engine should stop first or both might stop at about the same time - leads me to beleive that the understanding amongst the population of 135 pilots is clearly appropriate (not) - carry on.

Anyone with a clear understanding of the system care to explain what scenario leads to a double engine stoppage ? Just incase there is any 135 pilot out there who doesn't know..

What are the combinations of possible failure with 12 hoses 6 fuel pumps and 4(?) non-return valves - does the pilot need to understand that? No - not if it's all working properly i guess.

Remember the A109 in Wales because of the misunderstanding of a transfer pump failure?
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Old 13th Jan 2014, 05:51
  #991 (permalink)  
 
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Quote:
Thats the procedure according FLM. A dry running fuelpump gives a CAUTION and has to be switched off. So when in hover atttitude, the FWD pump will be the first when the main tank is coming to around 60 kg. In cruise flight ( nose low ) it will be the AFT pump. You have to consider it, when transitioning to cruise after long hover flight and low fuel in main tank -> AFT pump off and FWD pump ON again!!!


Skadi. Thank you very much. That is exactly as I imagined it would be.
And I already wrote this in the Clutha-thread ( post # 1429ff ) ....

skadi
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Old 13th Jan 2014, 17:27
  #992 (permalink)  
 
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AnFi,

Anyone with a clear understanding of the system care to explain what scenario leads to a double engine stoppage ? Just incase there is any 135 pilot out there who doesn't know..
Police helicopter crashes onto Glasgow pub, thread. Post 1471

There is also a very good post by Giovanni cento nove back in 2004 I think, about the 135 fuel system, but can't remember what thread.



Ah just found it! Post 83 this thread.

Last edited by PieChaser; 13th Jan 2014 at 17:39.
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Old 13th Jan 2014, 18:27
  #993 (permalink)  
 
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Post 83 on this thread

Gosh!! what a knowledgeable piece of writing.
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Old 13th Jan 2014, 20:19
  #994 (permalink)  
 
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the post from 83 to 114 are essential reading for 135 pilots. Complexity and permutations as described there make 'pilot error' inevitable - it's a shame they call it pilot error...
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Old 14th Jan 2014, 12:17
  #995 (permalink)  
 
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Complexity and permutations as described there make 'pilot error' inevitable - it's a shame they call it pilot error...
The original intent of PPRuNe was to allow pilots to air safety issues without fear of action being taken against them. If pilot error is inevitable then why hasn't a single? PPruNer 135 pilot posted about it? OK, many pilots choose to post pretty openly so their real ID is obvious but they can still open a new alias here, via a VPN if needed.
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Old 14th Jan 2014, 14:25
  #996 (permalink)  
 
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Up to date 44% of the whole fleet have been checked and 2% had faulty indications:

EC135 fuel probe malfunctions in 2% of cases - 1/14/2014 - Flight Global

skadi
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Old 23rd Jan 2014, 19:11
  #997 (permalink)  
 
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Do you not realise, the people from the Crash thread also post on here, so your answers aren't going to be any different.
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Old 23rd Jan 2014, 20:02
  #998 (permalink)  
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Originally Posted by Robin400 View Post
I am sorry for being a pain,I have been banned from the Glasgow forum for asking to many dumb questions.
And you will be from Rotorheads unless you heed that this forum is for

Rotorheads A haven for helicopter professionals to discuss the things that affect them
We accept that you aren't a helicopter professional, but to persist in asking what you agree are 'dumb questions' is stretching the friendship when the professionals who post here have been more than helpful in their previous responses.
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Old 26th Jan 2014, 10:33
  #999 (permalink)  

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Trying to bring the fuel talk here, rather than the Glasgow thread.

AnFI (really!)
It is patently obvious that, with such a high unuseable fuel quantity, the cockpit situation faced by this pilot may well have left him with an excessively confusing and unexpectedly complex set of actions. Maybe unpredictable issues of timing wrt Governor response rates and pilot action. Everything points to that.
"Confusing and unexpectedly complex set of actions!"

LOW FUEL 1 and/or2

Check fuel contents
If pos contents, check XFER pumps on
Check cb's in

If remains on, switch off bleed air
Land within 10 mins

(That Land being an immediate action!)
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Old 26th Jan 2014, 10:52
  #1000 (permalink)  

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AnFI(really!)'

Where does the fuel pressure warning come into your theory?

Your swimming pool emptying with a straw as opposed to a thimble 'parallel' has no relevance, as the transfer pumps are at the bottom of the 'pool', so the transfer system is more like a bath plug than a straw! Likewise for the supply, as when the fuel pressure caption comes on you switch on the prime pump!

Thank you Arkroyal, would that be sufficient fuel in the supply tanks or the main?
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