Both engines toasted

[Flying Kiwi]

Little birdie told me a Q-300 cooked both engines at NZPM yesterday. How so? :ooh:

[Hugh Jarse]

FK,

There's no torque or temperature limiting on the PW 123 powerplants, so they can be overtorqued/temped. There's also a bit of lag in engine response (and torque) about mid-way through the power lever range which, if not anticipated can lead to a rapid (coarse) increase in torque. I suspect it's a characteristic of the fuel scheduling. It's not an issue in day-to-day operation, just something to be aware of:E

Some (not all) PW 121's exhibit similar characteristics.

[c100driver]

:{

Done by a pilot, on the ground with both engines shut down!

[Pimp Daddy]

There's also a bit of lag in engine response (and torque) about mid-way through the power lever range which, if not anticipated can lead to a rapid (coarse) increase in torque.

Yeah - but the PW123 has pretty good transient limits, you'd have to give it a serious wodge of power then sit there and pick your nose for a fair amount of time before you "toast" the engines.

[gaunty]

Aaah the old engine shut down and the engine winding down with the fuel pumps still blazing away trick.:{

Ground power relay? or the unit itself. I think you will get the T/prop manufacturers to admit they get more toasted engines from ground ops/ground power U/S/running out of fuel/dodgy relays and plugs just falling out at the "right time" than just about any other reason.

We spend a gazillion dollars servicing the aircraft but the last thing we seem to check is the ground power unit.

This is a real case of it ain't over till its over and the fat lady sings, and a trap for even the most wary.:{

[eureka]

Is it true that a Dash 8 burned out two engines on the ground in Palmerston North? How would you do that? Don't they have safety things to stop that? How dangerous was it for us the travelling public? How much will it cost?:mad: loads i expect.

[Hugh Jarse]

:{

Done by a pilot, on the ground with both engines shut down!You've lost me there, c100driver:confused:

Perhaps if the condition levers were moved to "fuel off" then accidently back to "start/feather" while the donks are spooling down? Is that what you're implying?

[trommel]

Cl's were placed back at feather after shutdown, enough internal rotation to give fuel flow and ignition but with no air flow, i heard the props could not be rotated after second shutdown :uhoh:

[Hugh Jarse]

That'll do it!:eek:

The smoke effects would have looked spectacular:\

[Hanz Blix]

I'd imagine NSN sending out an ops not "Thall shall not touch thy conditions levers after shutdown".

Bugger for the boys involved, hopefully those rugs don't have to be used to much:eek:

hanz

[Cloud Cutter]

Hugh, apparently so! Big billows of thick black smoke. From what I've heard, whoever was moving the condition levers to cutoff, thought they felt a bit strange, so decided to give them a few good 'full and free' checks. Doh!!! My guess is they won't do that again.

[sexy time]

CC,

It is ignorant comments like that, that will see you being a wee boy in the right hand sight of a 1900 for the rest of your days!

[incidentreport]

I think I'll cool my heels for a few weeks, because all I'm capable of is abusive retorts.

Tid Edit

[pakeha-boy]

mate...forget the speculation...read the local paper...they will know exactly,to the detail what will have happened:} :}

[Cloud Cutter]

Sexy time

Sorry if I hit a nerve.

There is nothing ignorant about my post. It is 100% correct from my part, that is what I've heard (this is a rumour network). If what I've heard is in fact incorrect, then please feel free to correct me. I don't have time for your personal attacks, try being objective, more people will listen to you.

[deadhead]

CC, it wasn't so much what you said, more like how you said it - like you were dining out on someone else's misfortune ("d'oh! My guess is they won't do that again"). Have to admit the first thing I thought when reading that was "Wow! What a guess, Einstein!" But I've been on this forum since it began in 1996 (despite my title claiming 1999) and you get to know who the plonkers are - and you aren't (usually) one of those.

Just remember, despite how good we think we are, this fact will never change: there but for the grace of God, go we.

BTW, hands up those who have been specifically trained NOT to move fuel levers out of cutoff when N1 (or the Q300 equivalent) is still above a specific amount...and using common sense does NOT count for the purposes of this question!

Cheers
:ok:

[trommel]

Hindsight makes us all experts. Introducing a brand new type can be fraught with danger, Other airlines within NZ and Auz have had some incidents much worse than this when introducing a new type.

This sort of incident can happen (very easily) to anyone who is relatively new to a type. Best not to be to critical it may be you one day.:)

[Hugh Jarse]

Deadhead,
It's common knowledge, not only for the dash, but for any turbine engine that once you select fuel off that you would never reselect it back to on for any known reason until the engine has stopped.

However, the typical engine shut-down sequence for the Dash 8 is that when the engines have been run (condition levers max), the condition levers are moved to start/feather for 30 seconds prior to selecting fuel off. There is a detent between each position (min, start/feather and fuel off), but it is VERY easy to pull the condition levers out over both the detents and accidently go directly to fuel off and miss start/feather altogether. It's also VERY easy to go "oops" and reselect start/feather in an effort to recover the situation, with potentially expensive results.

At the very least you get an impressive smokescreen good enough to turn out the firies, at worst you melt metal.

Lots have done it, and no doubt more will.

[Cloud Cutter]

deadhead

Fair call, thanks for your candid response. I guess I was trying to make light of the situation, and went a bit far. Of course I feel sorry for the poor pilot who made the mistake, and yes, while in the comfort of my armchair I can say there are certain things I would and wouldn't do in an aircraft, I agree that we all make mistakes, and unfortunately sometimes this sort of thing will happen.

My apologies if I offended anyone.

*pulls head in*

[Capt Claret]

It's not unknown for turbines to not shutdown with the selection of fuel off due kinked cables, dud HP fuel valve, or whatever.

Though I've not had to do it, I have seen on more than one occasion, the fuel lever moved forward and then slammed home to shut the fuel off.

[sir.pratt]

every turbine pilot should have to rig an fcu before they use it - then they might learn to appreciate how fragile they really are.

in fact, how many turbine drivers actually know 1. where the fcu is, 2 what it does, 3. what does fcu mean?

and not shutting down is not really a problem - that's what the firewall T handle is for.....

[pakeha-boy]

well sir pratt....why dont you do us all a favour and share your wisdom....its been donkeys since I flew a Turbine and your "refresher course" would be of interest...thats of course if you know....its the Fuel Control Unit and it.........................

[deadhead]

Deadhead,
It's common knowledge, not only for the dash, but for any turbine engine that once you select fuel off that you would never reselect it back to on for any known reason until the engine has stopped.

Hi Hugh
My question specifically excluded "common knowledge/sense", it was purely intended to raise the point that it is likely no-one has been specifically trained not to move the said levers out of said position under said circumstances at all. Relying on "common knowledge" is too big (and in this case, too expensive) a gamble in our job, as I'm sure you understand. There is no substitute for experience, or in its absence, good training.
And that leads me to the next question: using your terminology, what constitutes a "stopped" engine? If it is when all rotating parts have stopped rotating, how do we determine this? By instruments? Some turbines I flew (eg Garrett) had RPM gauges so small you couldn't tell when it hit the zero stop, and in others they lost electrical power late in the shutdown sequence so you didn't know! So you had to assume that after a few minutes had elapsed, you could be assured that, indeed, the engines were "shut down".
So then, assuming the Dash 8 has RPM gauges that still have power throughout the shutdown sequence, how long does it take for the N1 to reach zero? Possibly some minutes, and if that is the case who is trained to understand that the Dash 8 engine takes several minutes before it is "stopped?"
Interesting.

[sir.pratt]

i'll stick to my turboprops - virtually every night i do some rigging. you stick to your computer

[Hugh Jarse]

Gidday Deadhead.

My question specifically excluded "common knowledge/sense", it was purely intended to raise the point that it is likely no-one has been specifically trained not to move the said levers out of said position under said circumstances at all.
It's impossible to offer you an answer without including common sense (as opposed to common knowledge). In my experience over the years I've never observed a trainee or expeienced pilot select the mixture from idle cutoff back into the operating range either unintentionally or intentionally (piston engine). The decision (and intent) is to stop the engine so there is no logical reason why you would want to do it (move it from idle cutoff).

Although the condition levers on the Dash carry out several functions (including fuel shutoff), one could still draw a common thread between its function, and that of the mixture lever on a piston engine (purely speaking in terms of them being the primary control of fuel for startup/shutdown).

It's like turning the key off in your car - Why would you switch it back on once you've decided to turn it off? I know it's being over simplistic, but it's illogical (apologies to Mr. Spock).

I'm aware of a number of incidents involving the inadvertant selection of fuel off and back to start feather. All were as a result of accidently moving the condition lever through the shutoff detent (ie there was never the intention of shutting down the engine - only feathering), then realising the error, and quickly moving it back to start/feather. This typically has occured during an abnormal situation such as an ECU malfunction (PW120). I know of nobody who has ever intentionally selected fuel off, then back on in the Dash.

My opinion is that the design of the detents could be better. As for the training aspect, I think there was paperwork issued stating that in the event of an inadvertant selection to fuel off, the condition lever/s should just be left there.

And that leads me to the next question: using your terminology, what constitutes a "stopped" engine? If it is when all rotating parts have stopped rotating, how do we determine this? By instruments? Some turbines I flew (eg Garrett) had RPM gauges so small you couldn't tell when it hit the zero stop, and in others they lost electrical power late in the shutdown sequence so you didn't know! So you had to assume that after a few minutes had elapsed, you could be assured that, indeed, the engines were "shut down". Yes, I've got a little time on Garretts, too. Being a fixed shaft engine, generally if I looked out the window and the prop wasn't turning, I assumed the internal rotating components were also not rotating. :E

The run down time of the PW12x varies, but the NH gauges are reasonably accurate. When I wrote "stopped", I meant NH reads zero (FWIW). Limitations for start are in our engineering manual. The correct handling techniques of the condition levers are taught at type endorsement level in our company.:)

[deadhead]

We're getting close.

I think the point here was that the guy possibly wasn't specifically trained to confirm the engines were shut down by checking NH was zero. Assuming that he knew and understood not to move the condition levers out of fuel off until the engine had shut down, it seems to me that he thought the engine was in fact shut down. The reason he moved the levers out of fuel off was in an attempt to diagnose a possible rigging issue, something even an idiot wouldn't do if they thought the engine was still running.

So then the question becomes: why did he believe the engine had completed the shutdown sequence? What cues was he trained to use? Do dash 8 pilots monitor the engines until NH reaches zero, and then verbalise this? How long does it take for the NH to reach zero? I'm not advocating this as a method, just wondering what happens. Maybe some other dash drivers might like to comment.

Touche re the good ol' Garrett. :O

[Hugh Jarse]

I think the point here was that the guy possibly wasn't specifically trained to confirm the engines were shut down by checking NH was zero. Assuming that he knew and understood not to move the condition levers out of fuel off until the engine had shut down, it seems to me that he thought the engine was in fact shut down. The reason he moved the levers out of fuel off was in an attempt to diagnose a possible rigging issue, something even an idiot wouldn't do if they thought the engine was still running.
I think you are treading into engineering territory Deadhead, when you write about checking rigging. That's the domain of the engineer, not the pilot. As a pilot, there is nothing in the Bombardier manuals which require the pilot to carry out engineering tasks. An engineer would carry out the procedure him/herself, rather than asking the pilot to do it. After all, they have a far more intimate knowledge of the donks than us.

Nevertheless, the specific case in question is out of my domain. I don't know whether it was pilots or engineers at the controls, and what the circumstances were behind the events. I just hope no-one gets crucified over what mos likely was an innocent mishap.

There's no requirement with the PW12x to monitor Nh or Np to any specific value as the engine runs down. The reason is that the condition lever remains at fuel off until the next engine start. Unlike the Garrett, where you hold the engine stop buttons in until a certain RPM. (for different reasons):)

As for the subject of this thread, I have no idea whether pilots or engineers were at the controls. I just hope nobody gets crucified over what was probably an honest mishap.

[deadhead]

Thanks Hugh. You prompted me to dig a little deeper, so spoke to someone closer to the event than I. He said that the person was a check and training captain who was planning to write up the fact that the condition levers were stiff to operate even with the friction loose. He was simply obtaining information for the engineers rather than attempting to fix it himself, not an unreasonable thing to do.
He also said that the pilot was not stood down, and that no disciplinary action will be taken. That is good news.:)
He also said that their SOPs have already been amended accordingly, so looks like lesson learned, albeit an expensive one...
And of course the best part is that no-one was hurt, at least not physically!:ok:

[Cloud Cutter]

Right, I guess that settles it then. A simple mistake, and lessons learned (for all of us who operate similar engines).

Shal we move on.

[sexy time]

Deadhead,

Thanks for getting the facts and sharing them correctly!

Cheers

[Waka Rider]

Without wanting to point,poke throw stones or sticks. Does Air Nelson let F/O's start and shut down engines. This is to compare and contrast different Sop's. Personally I am a big believer in NHP for the sector starting and shutting down the engines. It brings about very good monitoring of the start and importantly the shutdown by both crew. It also allows the skipper to be in a good monitoring position.

[pakeha-boy]

Waka mate....agree totally ....our procedures (SOP,s) have the F/O start but not shut down.........this gives the capt the ability to hold his coffee......and his cucumber sammy and not deal with the tivialities of starting ...love it....the piggy hunting was beauty....

sir pratt....we have a FADEC....A computer,of sorts,that stops us from frying engines....handy little thing I reckon....no rigging or # 8 wire required

[haughtney1]

Waka.....hmmm an airbooos start?..dontcha press a button and move a lever into a detent? (caught a jumpseat on a company 330 the other day...and took notice for a change:E )

[Waka Rider]

Haughtney have no idea about our Airbus but this was our procedure with regard to NHP starting and shutting down on the Dash 8-300, ERJ145, RJ 100 and B777. On the B777 its pretty simple with autostart you just have to remember to toggle the switch then put fuel to run. Which yours truely has even forgotten to do. Gives you some idea why I am better off trying to operate modern aircraft. Hoping Boeing create something like those clap on clap off lights. Thats an idea for the 787 aye boys. Pleased to say its a beautiful day in Tauranga 22 degrees sunshine not a cloud in sight.

[sir.pratt]

sir pratt....we have a FADEC....A computer,of sorts,that stops us from frying engines....handy little thing I reckon....no rigging or # 8 wire required

i did know that - that's what i meant (but you knew i knew that...:)

and it's not #8 wire, but black magic, that makes all those little levers talk to each other in a way that they don't all get tangled up

[pakeha-boy]

Black magic....yeah mate,thats exackery what is.....great minds thinking alike:}

Waka.....if your down at the "Dolphin" have a couple for me mate

[haughtney1]

PB, I reckon hes on the Maungatapu bridge catchin spratts:E