Police helicopter crashes onto Glasgow pub
Join Date: Feb 2005
Location: Australia
Posts: 1,957
Likes: 0
Received 0 Likes
on
0 Posts
and possibly hundreds, of feet.
As I have stated before I have seen the result of a power on overpitch from about 30 to 40 feet, 2 up in a R22, full fuel, I.E. MAUW or better, both succumbed not long after impact, but blades were still not showing the classic signs of overpitch bend.
It is a critical difference those extra few feet, twenty feet is survivable in most even without a blemish in some, but hundreds of feet usually leaves the Tail Boom with many fractures.
Looking at the fuel system schematic diagram again, I am struck by the apparent absence of a means to differentially fill the supply tanks. When there is fuel in the main tank, this isnt necessary, as the transfer pump(s) supply fuel to each supply tank faster than the engines can use it, so the supply tanks fill to the overflow, keeping them topped up, and the surplus fuel drains back into the main tank. Similarly, any fuel which "spills" out of the supply tanks via the overflow is replenished.
However, the diagram shows a single pipe feeding both tanks, which would suggest that any fuel being supplied from the main tank will be shared more or less equally with each supply tank. Fine while there is fuel in the main tank. Once the main tank has been exhausted,(as IMHO it was here) the supply tank levels begin to fall below full. Fuel spillage back into the main tank during manoeuvering would not necessarily be equal from each tank, depending on the manoeuvers, but the return feed from the main tank (assuming the transfer pumps were still on) would be. The resultant assymetry (beyond the designed assymetry) in supply tank contents would have the effect of altering the gap between each supply tank running out. Depending on the combination of manoeuvers, it could lengthen the gap, or shorten it....
However, the diagram shows a single pipe feeding both tanks, which would suggest that any fuel being supplied from the main tank will be shared more or less equally with each supply tank. Fine while there is fuel in the main tank. Once the main tank has been exhausted,(as IMHO it was here) the supply tank levels begin to fall below full. Fuel spillage back into the main tank during manoeuvering would not necessarily be equal from each tank, depending on the manoeuvers, but the return feed from the main tank (assuming the transfer pumps were still on) would be. The resultant assymetry (beyond the designed assymetry) in supply tank contents would have the effect of altering the gap between each supply tank running out. Depending on the combination of manoeuvers, it could lengthen the gap, or shorten it....
Avoid imitations
Join Date: Nov 2000
Location: Wandering the FIR and cyberspace often at highly unsociable times
Posts: 14,573
Received 415 Likes
on
218 Posts
It will be interesting to see what the hydraulic systems were doing at the time?
I've not been in the 135 simulator. What happens when both donkeys fail, how does it handle?
I've not been in the 135 simulator. What happens when both donkeys fail, how does it handle?
Quote:
It will be interesting to see what the hydraulic systems were doing at the time?
I've not been in the 135 simulator. What happens when both donkeys fail, how does it handle?
Surely you aren't thinking that the hydraulics are powered by the engines?
It will be interesting to see what the hydraulic systems were doing at the time?
I've not been in the 135 simulator. What happens when both donkeys fail, how does it handle?
Surely you aren't thinking that the hydraulics are powered by the engines?
Avoid imitations
Join Date: Nov 2000
Location: Wandering the FIR and cyberspace often at highly unsociable times
Posts: 14,573
Received 415 Likes
on
218 Posts
Depending on type, the controls might not be rigid, but tending to stir the pilot's arms around the cockpit due to unopposed aerodynamic feedback forces.
But as the hydraulics are main rotor gearbox powered, with full system pressure being available at very low rotor rpm (well below the limits supporting flight), it's unlikely to be a relevant factor. In any event, a pilot suffering a double hydraulic failure would hardy switch off both engines.
But as the hydraulics are main rotor gearbox powered, with full system pressure being available at very low rotor rpm (well below the limits supporting flight), it's unlikely to be a relevant factor. In any event, a pilot suffering a double hydraulic failure would hardy switch off both engines.
Depending on type, the controls might not be rigid, but tending to stir the pilot's arms around the cockpit due to unopposed aerodynamic feedback forces.
All somewhat off thread - if there is any common thread left now....
Avoid imitations
Join Date: Nov 2000
Location: Wandering the FIR and cyberspace often at highly unsociable times
Posts: 14,573
Received 415 Likes
on
218 Posts
You chaps really aren't using your imagination!
Join Date: Jul 2000
Location: Nova
Posts: 1,242
Likes: 0
Received 0 Likes
on
0 Posts
Are you waiting for someone to beg for your "book" answer?
Not at all. Not least because I have absolutely no intention whatsoever of expanding on my opinion! That would be total speculation on my part. I'm simply saying that anyone (robin and pie) who thinks a twin loses all power ONLY when it runs out of fuel, or both engines are closed down isn't using their imagination, that's all. I haven't said you, or other experienced professionals won't have considered other possibilities!
Personally I don't think either fuel starvation or TR failure is necessarily a good fit with the witness statements or the lack of a successful autorotation!
AIMVHO of course.
A good while yet before we will know any more.
Join Date: Jul 2011
Location: Offshore
Age: 73
Posts: 143
Likes: 0
Received 0 Likes
on
0 Posts
Pprune at its very worst... What a shame!
With all due respect, comments from Piechaser, Falcon900 and Robin 400 show clear lack of knowledge, relevant experience and even intelligence.
Igniters, fuel starvation, fuel exhaustion, hydraulics blah blah blah... what can they hope to contribute from their clearly evident (and oft confessed) oceans of ignorance?
Speakings as one with a fair bit EC experience and who knew (and greatly respected) the pilot in this incident, I view the avalanche of recent bull
t comments as having served only to contaminate this highly-valued website and expose certain contributors in an accurate but most unfavourable light.
Toodle-pip..must go... I'm going to exercise my God-given right to comment on a brain-surgery website. I know absolutely -all about the topic and therefore have nothing worthwhile to contribute but Oh Boy! I'm going to have my say. 
Igniters, fuel starvation, fuel exhaustion, hydraulics blah blah blah... what can they hope to contribute from their clearly evident (and oft confessed) oceans of ignorance?
Speakings as one with a fair bit EC experience and who knew (and greatly respected) the pilot in this incident, I view the avalanche of recent bull
t comments as having served only to contaminate this highly-valued website and expose certain contributors in an accurate but most unfavourable light.Toodle-pip..must go... I'm going to exercise my God-given right to comment on a brain-surgery website. I know absolutely
-all about the topic and therefore have nothing worthwhile to contribute but Oh Boy! I'm going to have my say.
Join Date: Dec 2007
Location: UK
Age: 80
Posts: 158
Likes: 0
Received 0 Likes
on
0 Posts
Electrical load.
I understand that the generators are driven from the gearbox of each engine.
During autorotation what effect will a heavy electrical load (landing light, search light) have on the rotor rpm.
Could this be the reason the rotor blades rotational speed reduced below that expected by a very experienced captain resulting in a heavy landing.
I suspect very few pilots will have carried out autorotation to land with both engines shutdown.
Unless a descent is vertical the rad alt can be very misleading over a built up area as one can not be certain whether the return is from the ground or the top of a structure.
An easterly approach into JSY is a good example.
During autorotation what effect will a heavy electrical load (landing light, search light) have on the rotor rpm.
Could this be the reason the rotor blades rotational speed reduced below that expected by a very experienced captain resulting in a heavy landing.
I suspect very few pilots will have carried out autorotation to land with both engines shutdown.
Unless a descent is vertical the rad alt can be very misleading over a built up area as one can not be certain whether the return is from the ground or the top of a structure.
An easterly approach into JSY is a good example.
With all due respect, comments from Piechaser, Falcon900 and Robin 400 show clear lack of knowledge, relevant experience and even intelligence
During autorotation what effect will a heavy electrical load (landing light, search light) have on the rotor rpm
Do you think a light bulb is going to consume sufficient power to overcome the kinetic energy being derived from a 3 tonne helicopter descending at 2,000 ft/min?
Join Date: Jan 2010
Location: Midlands
Age: 78
Posts: 119
Likes: 0
Received 0 Likes
on
0 Posts
talkpedlar
Totally agree - the immediately following post just proved it.
I am reminded of the round and round video clip of an earlier post.
Please - no more idle speculation. In 1900 odd posts it's bound to have been debated already. The only thing we want now is hard facts about this most extraordinary and perplexing accident.
I am reminded of the round and round video clip of an earlier post.
Please - no more idle speculation. In 1900 odd posts it's bound to have been debated already. The only thing we want now is hard facts about this most extraordinary and perplexing accident.
Last edited by Old and Horrified; 22nd Jan 2014 at 18:32. Reason: grammar
Avoid imitations
Join Date: Nov 2000
Location: Wandering the FIR and cyberspace often at highly unsociable times
Posts: 14,573
Received 415 Likes
on
218 Posts
Robin400,
Generator load will have little effect on main rotor rpm. When multi-engined helicopter generators drop off line, automatic load shedding is often designed in. But this is for reasons of generator loading, certainly not to maintain main rotor rpm during autorotation! With both engines shut down, the landing lights/search light would be powered by the aircraft battery, not a generator.
Autorotations are not flown on instruments in VMC, especially in the final stages. It's highly unlikely that radalt inconsistency was a factor here.
Please now give it a rest. As you can see, folks are beginning to lose patience.
Generator load will have little effect on main rotor rpm. When multi-engined helicopter generators drop off line, automatic load shedding is often designed in. But this is for reasons of generator loading, certainly not to maintain main rotor rpm during autorotation! With both engines shut down, the landing lights/search light would be powered by the aircraft battery, not a generator.
Autorotations are not flown on instruments in VMC, especially in the final stages. It's highly unlikely that radalt inconsistency was a factor here.
Please now give it a rest. As you can see, folks are beginning to lose patience.
Join Date: Jul 2000
Location: Nova
Posts: 1,242
Likes: 0
Received 0 Likes
on
0 Posts
Robin
I have no knowledge of the EC135, but I am familiar with other very similar (if older!) helicopters.
Each engine would normally be equipped with a starter/generator, typically 28VDC. this may or may not be connected to the engine's accessory gearbox.
Since each engine will always have a freewheel assembly, preventing any engine malfunction 'dragging down' Main Rotor RPM. The main gearbox is, in all cases effectively isolated from the engines (and generators) during true autorotation.
So your theory doesn't hold water! Though I'm not sure the people who know the specific EC135 answer will bother to answer your question.
As I have stated earlier, an autorotative landing is a visual manoeuvre. During the final flare and landing, frankly there wouldn't be time for Rad Alt information to be effectively used. Yes a landing light would be useful but that might not be provided from the battery bus alone???
It's EXTREMELY difficult to imagine a final flare to be so badly mishandled, even in low ambient light in a city centre, that the MR RPM, is completely spent! IMVHO that cannot be the only explanation for virtually zero RRPM!
I know of two twin helicopters that have run out of fuel whilst airborne, and two very large jet liners. In all cases everyone walked away! Such a scenario shouldn't have come as such a surprise to this talented pilot that he was not able to have a pretty good stab at an autorotative landing.
As I keep saying, AIMVHO of course!
I have no knowledge of the EC135, but I am familiar with other very similar (if older!) helicopters.
Each engine would normally be equipped with a starter/generator, typically 28VDC. this may or may not be connected to the engine's accessory gearbox.
Since each engine will always have a freewheel assembly, preventing any engine malfunction 'dragging down' Main Rotor RPM. The main gearbox is, in all cases effectively isolated from the engines (and generators) during true autorotation.
So your theory doesn't hold water! Though I'm not sure the people who know the specific EC135 answer will bother to answer your question.
As I have stated earlier, an autorotative landing is a visual manoeuvre. During the final flare and landing, frankly there wouldn't be time for Rad Alt information to be effectively used. Yes a landing light would be useful but that might not be provided from the battery bus alone???
It's EXTREMELY difficult to imagine a final flare to be so badly mishandled, even in low ambient light in a city centre, that the MR RPM, is completely spent! IMVHO that cannot be the only explanation for virtually zero RRPM!
I know of two twin helicopters that have run out of fuel whilst airborne, and two very large jet liners. In all cases everyone walked away! Such a scenario shouldn't have come as such a surprise to this talented pilot that he was not able to have a pretty good stab at an autorotative landing.
As I keep saying, AIMVHO of course!
Do you think a light bulb is going to consume sufficient power to overcome the kinetic energy being derived from a 3 tonne helicopter descending at 2,000 ft/min?
So.....double that Square Root number and what do you get.....why that amounts to almost a Catastrophic increase....doubled even!
Join Date: Dec 2007
Location: UK
Age: 80
Posts: 158
Likes: 0
Received 0 Likes
on
0 Posts
Question for all the expert's
Why has nobody made me aware the starter generator provides the electrical power and not a generator driven by the rotor accessory gearbox.
With both engines failed power is only available from the battery.
Why has nobody made me aware the starter generator provides the electrical power and not a generator driven by the rotor accessory gearbox.
With both engines failed power is only available from the battery.
Last edited by Robin400; 22nd Jan 2014 at 13:40.
Join Date: Dec 2007
Location: UK
Age: 80
Posts: 158
Likes: 0
Received 0 Likes
on
0 Posts
Portrait of a Machine
What nudity as beautiful as this
Obedient monster purring at its toil;
Those iron muscles dripping oil,
And the sure-finger rods that never miss?
This long and shinning flank of metal is
Magic that greasy labour cannot spoil;
While this vast engine that could rend the soil
Conceals its fury with a gental hiss.
It does not vent its loathing, it does not turn
Upon its makers with destroying hate.
It bears a deeper malice; lives to earn
Its master's bread and laughs to see this great
Lord of the earth, who rules but cannot learn,
Become a slave of what his slaves create.
Louise Untermeyer
Obedient monster purring at its toil;
Those iron muscles dripping oil,
And the sure-finger rods that never miss?
This long and shinning flank of metal is
Magic that greasy labour cannot spoil;
While this vast engine that could rend the soil
Conceals its fury with a gental hiss.
It does not vent its loathing, it does not turn
Upon its makers with destroying hate.
It bears a deeper malice; lives to earn
Its master's bread and laughs to see this great
Lord of the earth, who rules but cannot learn,
Become a slave of what his slaves create.
Louise Untermeyer
Last edited by Robin400; 22nd Jan 2014 at 14:53.