Police helicopter crashes onto Glasgow pub: final AAIB report
Of course, in a modern glass cockpit - 139 for example, you get to see Nr, Nf and all other engine parameters on one screen so it is not a case of having to concentrate on the Nr gauge since all the info you need is in one place, unlike older analogue displays where manufacturers put the Nr gauge in all sorts of random locations.
The other point is that aural cues are usually available - either from an Aural Warning Generator or a simple beeping horn.
On the 365 N3 for example you knew that you had the Nr within limits when both the high and low Nr horns were silent and the low Nr horn was particularly useful for OEI work - pull until it goes off, then back off enough to quieten it again and you didn't have to look at the Nr gauge to know you had the desired 350 Nr.
I presume the 135 has similar warnings.
The other point is that aural cues are usually available - either from an Aural Warning Generator or a simple beeping horn.
On the 365 N3 for example you knew that you had the Nr within limits when both the high and low Nr horns were silent and the low Nr horn was particularly useful for OEI work - pull until it goes off, then back off enough to quieten it again and you didn't have to look at the Nr gauge to know you had the desired 350 Nr.
I presume the 135 has similar warnings.
Join Date: Dec 2006
Location: UK and MALTA
Age: 61
Posts: 1,297
Likes: 0
Received 18 Likes
on
4 Posts
Originally Posted by [email protected]
Of course, in a modern glass cockpit - 139 for example, you get to see Nr, Nf and all other engine parameters on one screen so it is not a case of having to concentrate on the Nr gauge since all the info you need is in one place, unlike older analogue displays where manufacturers put the Nr gauge in all sorts of random locations.
The other point is that aural cues are usually available - either from and Aural Warning Generator or a simple beeping horn.
On the 365 N3 for example you knew that you had the Nr within limits when both the high and low Nr horns were silent and the low Nr horn was particularly useful for OEI work - pull until it goes off the back off enough to quieten it again and you didn't have to look at the Nr gauge to know you had the desired 350 Nr.
I presume the 135 has similar warnings.
The other point is that aural cues are usually available - either from and Aural Warning Generator or a simple beeping horn.
On the 365 N3 for example you knew that you had the Nr within limits when both the high and low Nr horns were silent and the low Nr horn was particularly useful for OEI work - pull until it goes off the back off enough to quieten it again and you didn't have to look at the Nr gauge to know you had the desired 350 Nr.
I presume the 135 has similar warnings.
If the collective is not lowered quickly enough and the NR decays to the figure indicated with a High ROD, a deep stall occurs and the rotor stops very quickly. The OEM testing indicated this can happen in around 2 seconds when the conditions have been met. Its scary and it is the major lesson from this accident.
That's pretty much what you would expect in any single-engine helicopter?
There is a thing on each side of your head that is a pretty good Nr gauge as well.
Resilience to self preservation is a fine thing only if you are aware of the consequences!
I know an individual who was on a demo flight in a light twin and was sitting in the back seat. The demo pilot flicked one engine to IDLE and was demonstrating the OEI performance and on completing the demo entered
a brain fade and flicked the remaining engine to idle instead - as the two pilots looked at each trying to figure ot what the unexpected result was the individual in the back seat pushed the collective down with his foot!!
Probably lucky it was a twin derived from a single.
Resilience to self preservation is a fine thing only if you are aware of the consequences!
I know an individual who was on a demo flight in a light twin and was sitting in the back seat. The demo pilot flicked one engine to IDLE and was demonstrating the OEI performance and on completing the demo entered
a brain fade and flicked the remaining engine to idle instead - as the two pilots looked at each trying to figure ot what the unexpected result was the individual in the back seat pushed the collective down with his foot!!
Probably lucky it was a twin derived from a single.
Flight path management is paramount but we start by getting the pilot to invest in the idea that the Nr gauge is his most reliable indication of a complete power loss. From that concept he can build a strategy that works around the Nr gauge.
I have preached the importance of Main Rotor RPM from my earliest days flying helicopters.....As Helicopter Pilots we live and die by Rotor RPM or the lack of. Rarely, and I know not of a single case where a Rotor Overspeed killed someone....although I suppose it might have happened sometime in the history of helicopter flight.
In multi-engine helicopters....I place the Rotor Tach at the top of the list for analyzing engine malfunctions.....by suggesting a quick glance at the Rotor Tach shall give an indication of whether it is a High Side or Low Side failure (assuming a steady Collective position) by seeing if the Nr is higher or lower than set prior to the failure.
Torque Needles are the least useful of the gauges for use in deciding what kind of failure you have had.
N1/Ng, then N2/Nf/ then EGT/ITT and if necessary Oil Pressure and Oil Temp in that order.
Are we saying the same thing but in different ways?
Why would we want a high and low RPM horn?
I like the old Huey way...Light for high RPM and Light and Horn for Low RPM....makes for no confusion.
Why would we want a high and low RPM horn?
Crab I agree 100% with all you say. For the Low Aural Warning it works when the pilot is not over aroused (startled) but how many times do we see this aural warning being ignored when the brain is saturated
The only trouble is there are so many aural warnings in a modern helicopter that it can be difficult to work out which is the most important.
Rarely, and I know not of a single case where a Rotor Overspeed killed someone....although I suppose it might have happened sometime in the history of helicopter flight.
I like the old Huey way...Light for high RPM and Light and Horn for Low RPM....makes for no confusion.
Here as well as there, a false sense of security and the added complexity of a twin have been significant contributing factors to the accidents.
The 214ST accident report referenced above ("Most of the time") is instructive. Here's my takeaway.
1) Things happen FAST in a helicopter.
2) We pilots instinctively lower the collective upon ANY anomaly.
3) Having a 12,000-hour copilot with tons of multi-engine experience is virtually no help, thank you.
The bottom line of the Clutha Pub accident is that the PIC screwed up: He didn't have the transfer pump switches on for some reason. Now, you can analyze it to death...or 28 pages of PPRUNE drivel in this thread alone...but it doesn't change the fact that the pilot mismanaged his fuel...and then screwed up the (night, full-down) auto after a dual-flameout.
I know that in trying to explain or make sense of an accident...any accident...we sometimes go 'round and 'round, trying to figure out what mitigating factors could lead an experienced pilot to do something dumb. We naturally want to give the pilot every benefit of doubt. But we pilots are just human. We make mistakes. Sometimes we push when we should pull.
I made the same basic mistake in a BO105 once - left the transfer pump switches off. PHI was even nice enough to install little white lights on the dash to remind us dumb pilots to turn them on. But they were up at the top of the panel, under the glareshield and I missed them. Thankfully I was solo and it was daylight...and I was topped-off, so fuel from the main tank was feeding automatically into the supply tanks at cruise attitude. But I'll tell you, when I did my after take-off look-around of the cockpit my heart literally stopped when I saw the transfer pump switches. Just thinking about that day gives me the shivers. It is a mistake you make only once - if you live to correct it.
1) Things happen FAST in a helicopter.
2) We pilots instinctively lower the collective upon ANY anomaly.
3) Having a 12,000-hour copilot with tons of multi-engine experience is virtually no help, thank you.
The bottom line of the Clutha Pub accident is that the PIC screwed up: He didn't have the transfer pump switches on for some reason. Now, you can analyze it to death...or 28 pages of PPRUNE drivel in this thread alone...but it doesn't change the fact that the pilot mismanaged his fuel...and then screwed up the (night, full-down) auto after a dual-flameout.
I know that in trying to explain or make sense of an accident...any accident...we sometimes go 'round and 'round, trying to figure out what mitigating factors could lead an experienced pilot to do something dumb. We naturally want to give the pilot every benefit of doubt. But we pilots are just human. We make mistakes. Sometimes we push when we should pull.
I made the same basic mistake in a BO105 once - left the transfer pump switches off. PHI was even nice enough to install little white lights on the dash to remind us dumb pilots to turn them on. But they were up at the top of the panel, under the glareshield and I missed them. Thankfully I was solo and it was daylight...and I was topped-off, so fuel from the main tank was feeding automatically into the supply tanks at cruise attitude. But I'll tell you, when I did my after take-off look-around of the cockpit my heart literally stopped when I saw the transfer pump switches. Just thinking about that day gives me the shivers. It is a mistake you make only once - if you live to correct it.
I made the same basic mistake in a BO105 once - left the transfer pump switches off
https://www.atsb.gov.au/media/1358105/ao2007036.pdf
Following the 214 event above, the pilot was shown the door, court case had him reinstated. Pity is, the management of the time are still of the opinion "it was all his fault". No lessons learnt there, you can lead a horse to water...………..
Join Date: Aug 2000
Location: Liverpool based Geordie, so calm down, calm down kidda!!
Age: 60
Posts: 2,051
Likes: 0
Received 17 Likes
on
6 Posts
For all I write, I accept that Dave didn’t put the fuel in the right place and the EOL didn’t work. My argument is what is written about him post accident. If the fuel system gave him conflicting information (that was found on many many 135s post accident), then thereMAY be mitigating circumstances to his decision making process. So it’s not WHAT he did (no argument) it’s why?
Why is this really important?
So it doesn’t happen again................
Why is this really important?
So it doesn’t happen again................
Join Date: Dec 2006
Location: UK and MALTA
Age: 61
Posts: 1,297
Likes: 0
Received 18 Likes
on
4 Posts
For all I write, I accept that Dave didn’t put the fuel in the right place and the EOL didn’t work. My argument is what is written about him post accident. If the fuel system gave him conflicting information (that was found on many many 135s post accident), then thereMAY be mitigating circumstances to his decision making process. So it’s not WHAT he did (no argument) it’s why?
Why is this really important?
So it doesn’t happen again................
Why is this really important?
So it doesn’t happen again................
Dave may well have had sensible contents indications and the warnings did not make enough impact for him to make an earlier decision. Sadly, the underlying lesson is how we respond to the RED Low Fuel backstop warnings. As for the Auto....that could of been any one of us. The only thing we can do is get as much exposure to double OEI in the sim to try and improve our responses.
Join Date: Aug 2000
Location: Liverpool based Geordie, so calm down, calm down kidda!!
Age: 60
Posts: 2,051
Likes: 0
Received 17 Likes
on
6 Posts
Agreed 100%.
The FAI has taken a heck of a long time to convene, let’s hope our questions are answered properly. The families deserve that.
The FAI has taken a heck of a long time to convene, let’s hope our questions are answered properly. The families deserve that.
Join Date: Feb 2018
Location: North of the border in a dark place
Posts: 23
Likes: 0
Received 0 Likes
on
0 Posts
Well said kidda
For all I write, I accept that Dave didn’t put the fuel in the right place and the EOL didn’t work. My argument is what is written about him post accident. If the fuel system gave him conflicting information (that was found on many many 135s post accident), then thereMAY be mitigating circumstances to his decision making process. So it’s not WHAT he did (no argument) it’s why?
Why is this really important?
So it doesn’t happen again................
Why is this really important?
So it doesn’t happen again................
Fact....How long had the engines been running when they quit due to fuel starvation?
Dave (or any Pilot) should have had that fact worked into the situation along with the possibly confusing indications.
Ensuring both Transfer Pumps were switched on should have been part of that analysis of the problem.
We shall never know with absolutely certainty what he did or why....but we can all see what he did not do.
That is not a slam on Dave personally....anyone of us could have been in his seat and very likely could have made the same mistakes.
That is why trying to work out the puzzle for what happened that night is so difficult.
A well trained and experienced pilot who was thought well of those who flew with him and knew him....winds up in a tragic event as this.....is troubling because it could happen to us....any of us.
CVR's are not that expensive....why do we not install them as standard equipment defeats me.
Dave (or any Pilot) should have had that fact worked into the situation along with the possibly confusing indications.
Ensuring both Transfer Pumps were switched on should have been part of that analysis of the problem.
We shall never know with absolutely certainty what he did or why....but we can all see what he did not do.
That is not a slam on Dave personally....anyone of us could have been in his seat and very likely could have made the same mistakes.
That is why trying to work out the puzzle for what happened that night is so difficult.
A well trained and experienced pilot who was thought well of those who flew with him and knew him....winds up in a tragic event as this.....is troubling because it could happen to us....any of us.
CVR's are not that expensive....why do we not install them as standard equipment defeats me.
Join Date: Dec 2006
Location: UK and MALTA
Age: 61
Posts: 1,297
Likes: 0
Received 18 Likes
on
4 Posts
We do know, with a degree of certainty, was the Fuel Low Warnings appeared and were cancelled by the [crew]. This being recorded by the NV memory in the CAD system.
What we do not know, is what the graphic presentation looked like (the indication of where exactly the fuel was). This argument appears to be supported by several events after Dave's accident whereby the graphic indications of fuel did not match the warnings being delivered by the Red Low Fuel Backstop indicators. Dave's fuel contents indication system was subsequently tested and appeared to function normally. However, in the subsequent events, it was determined that only a minute amount of water in the Capacitance Sensor was enough to give an indication that the tank was full. The Thermistor fuel backstop Red Warnings are independent of the capacitance contents sensors.
Taken holistically, we could make an argument that Dave left his transfer pumps OFF. This caused his supply tanks to deplete to zero, triggering many warnings of FUEL LOW, Amber and Red. Why did he not react???? Maybe what he saw, and more importantly trusted above all else, was the graphic indications of where the fuel was. Maybe his supply tanks were indicating FULL, caused by a minute amount of water the capacitance sensors which subsequent to recovery of the helicopter post accident, had dried away. If you read the report, the amount of water required to create this illusion is miniscule. To accept this we would also have to accept that Dave did not realise the independent and robust nature of the Thermistor Sensors (providing Red FUEL LOW Warnings) and thus allowed himself to be "driven" by the contents indications alone.
In conclusion, I do not think we can accuse Dave of not managing his endurance appropriately.
It is for these reasons, that many of us conclude that the learning points are, 1. The importance of the Red FUEL LOW warnings, regardless of what appears on the CAD Contents graphic indications. In addition, the crystal clear association between a FUEL LOW warning of any kind, and an immediate requirement to check the status of the Transfer Pumps (ON).
DB,
All that is well and good....except for the fact that "fuel remaining at touchdown" is supposed to be in the Supply Tanks with Transfer Pumps "ON".
In this case....it wasn't and they were not.
How is it possible to miss the Transfer Pumps being "OFF", and the Supply Tanks showing depletion of contents?
Are there not Caution Lights showing the Pumps being off?
In that series of aircraft one has to monitor three tanks...not just total fuel.
When it comes to believing Warnings and Indications....especially with Fuel when at minimum fuel levels (even if determined only by time in flight)...the prudent Soul ALWAYS goes with the most dangerous of the two.....ALWAYS.
Evidence clearly shows the Crew KNEW there was a fuel contents issue.
They may not have known the true extent of the problem....and as you state....if Dave did know of the independence of the two systems he made a fatal error in judgement.
If he did not...that shows a problem in Training and Qualification that set him up for a bad decision.
That the Transfer Pumps WERE OFF....when everything says they should have been ON.....there is not getting around that fact.
Had those Pumps been switched on and just one of them worked....this accident would not have happened.
Why were they OFF....why had Dave not switched them back ON and why did he not see and react to Cautions they were OFF?
I flew the 105 and 117 series of aircraft that used the same general fuel system as the 135.....we never turned the Transfer Pumps OFF....never!
We also closely monitored the fuel contents in all Tanks especially late in the flight.
All that is well and good....except for the fact that "fuel remaining at touchdown" is supposed to be in the Supply Tanks with Transfer Pumps "ON".
In this case....it wasn't and they were not.
How is it possible to miss the Transfer Pumps being "OFF", and the Supply Tanks showing depletion of contents?
Are there not Caution Lights showing the Pumps being off?
In that series of aircraft one has to monitor three tanks...not just total fuel.
When it comes to believing Warnings and Indications....especially with Fuel when at minimum fuel levels (even if determined only by time in flight)...the prudent Soul ALWAYS goes with the most dangerous of the two.....ALWAYS.
Evidence clearly shows the Crew KNEW there was a fuel contents issue.
They may not have known the true extent of the problem....and as you state....if Dave did know of the independence of the two systems he made a fatal error in judgement.
If he did not...that shows a problem in Training and Qualification that set him up for a bad decision.
That the Transfer Pumps WERE OFF....when everything says they should have been ON.....there is not getting around that fact.
Had those Pumps been switched on and just one of them worked....this accident would not have happened.
Why were they OFF....why had Dave not switched them back ON and why did he not see and react to Cautions they were OFF?
I flew the 105 and 117 series of aircraft that used the same general fuel system as the 135.....we never turned the Transfer Pumps OFF....never!
We also closely monitored the fuel contents in all Tanks especially late in the flight.
Join Date: Dec 2006
Location: UK and MALTA
Age: 61
Posts: 1,297
Likes: 0
Received 18 Likes
on
4 Posts
Hi SAS, you are absolutely right. However, in the EC135 the caution lights associated with the Transfer pumps work in reverse. When the cavitate (they heat up) they show a warning. The attitude of the fuselage can cause this when the main contents reduce to a certain level. The standard practice seemingly being to select the offending pump OFF to extinguish the caution. In PLOD ops, a combination of balls out forward flight to get to the task followed by prolonged hovering, offers the two extreme conditions of nose down and nose up respectively, causing in the right (sic) conditions, both pump lights to illuminate sequentially according to attitude.
Poor airmanship can cause the pilots to forget to switch them back on again. Without a CVR or FDR we can never know for certain how this transpired in this accident case.
Like I said, we do know for a fact that fuel was not in the supply tanks. We know for a fact that when the aircraft was inspected by AAIB the transfer pumps were positioned OFF. One prime pump (in the supply tank) was positioned ON. We can only assume the role Dave played in these switch selections including how the switches ended up in the positions they were.
To imagine how the fuel starvation eventually took place, you are right, we have to imagine that despite the general low fuel state, the multiple warnings the CAD NVM implies he received...and acknowledged (by a switch on the cyclic), he seemingly never checked if the transfers pumps were working. To then take it to the unfortunate conclusion of double flameout and poor auto leading to zero NR at approximately 400 feet, it takes a huge effort to imagine this all occurred in sequence without Dave ever once taking appropriate action.
The contents indication theory is just that. A theory. Its only merit is that it offers us an opportunity to maybe understand to some degree why Dave did not react to the sequence that unfolded. Was what he saw on the gauges different to what the Cautions an Warnings he received telling him? Its just one possible explanation as why his implied actions were at odds with what was happening.
Poor airmanship can cause the pilots to forget to switch them back on again. Without a CVR or FDR we can never know for certain how this transpired in this accident case.
Like I said, we do know for a fact that fuel was not in the supply tanks. We know for a fact that when the aircraft was inspected by AAIB the transfer pumps were positioned OFF. One prime pump (in the supply tank) was positioned ON. We can only assume the role Dave played in these switch selections including how the switches ended up in the positions they were.
To imagine how the fuel starvation eventually took place, you are right, we have to imagine that despite the general low fuel state, the multiple warnings the CAD NVM implies he received...and acknowledged (by a switch on the cyclic), he seemingly never checked if the transfers pumps were working. To then take it to the unfortunate conclusion of double flameout and poor auto leading to zero NR at approximately 400 feet, it takes a huge effort to imagine this all occurred in sequence without Dave ever once taking appropriate action.
The contents indication theory is just that. A theory. Its only merit is that it offers us an opportunity to maybe understand to some degree why Dave did not react to the sequence that unfolded. Was what he saw on the gauges different to what the Cautions an Warnings he received telling him? Its just one possible explanation as why his implied actions were at odds with what was happening.