false Indications

[Toni]

Hi There!

I''ve read Shawn Coyle''s The Art and Science of Flying Helicopters,and there is a section about false engine out indications for ex.number 1 down to 0 audio signal on ,but still having power!!!
My question is ,if one or more of you out there have got such experiencies or similar ones!
Thank''s!Hope I posted in a way you understand what I mean!!!

Toni

 

[DGP]

I"m not sure about the question but most turbine engine out warning systems run off of N1 speed sensers so if your engine tach generator or your N1 gauge packs it in you get an engine out warning light and horn even though the donkeys still runnin...check your dual tach and make sure your N2 is still on line before you start to panic...I''m sure this has happened to lots of guys...It''s happened to me at least a half dozen times.

 

[Dan]

Yes I know of someone who didn't check the guages after he got an engine out horn in a 206. In the ensuing panic he rolled off the throttle and auto'd to a very unsuccessful landing.
If your still flying that means the engine is still operating. The problem was just as mentioned earlier, N1 tach gave up the ghost and a perfectly good aircraft was neadlessly rolled up.
If this happens to you or if the real thing happens, just dump the collective then look at the guages to confirm your worst nightmare. If there is Tq indication, Auto relite not on,oil pressure, N2 100 %, you can always just pull in collective and clean your shorts.
Don't put all your pickles in one basket by reacting to fast.

If you ever timed a C20 from startup, it takes about 35 seconds from pushing the start button to idle, then another 10-15 seconds to 100 %. This means while flying at 1000 AGL with the average auto, decending at 2200 feet per minute. You have 35 seconds to first realize the engine quit, react to dropping the pole, then look for a spot to land, get out that mayday call, then react to trying to start the engine. Well you do the math before you are on the ground. One way or the other your going to be on it, in it or thru it. Only you can make it a soft or the "Oh Sh&t" landing.

Like always it's alot easier to be an arm chair critic well after the fact.

 

[MagSeal]

A number of years ago a guy named Ralph R. had just such an incident. The N1 tach generator cannon plug was cross threaded and managed to come loose, giving him an engine out warning. Due to his low altitude and speed, he had little time to react and promptly entered an auto, at the flare he yarded up the collective, and realized as he overtorqued the ship, that the stove was still going. Unfortunately there was a hard landing and some damage. A simple wire problem ended up costing alot of money. Good thing he was over a clearing and not trees.

 

[Randy_G]

I have always been taught to look for a secondary indication for every problem. If you get an engine out warning, did you get a large amount of yaw with it ?? If you didn't, chances are the engine is still up and running. Having had a snow-ingestion induced flame-out, I can assure you that there was a distinct sinking feeling, and a decent amount of yaw that accompanied the engine out warning. Thank you to who ever designed the auto-relight !!!

If you get an engine out warning, by all means start down on the pole, but before you go all the way to the trees, and roll up that a/c, check N2/Nr tach, TOT/EGT/ITT/whatever temp guage you've got. You might be pleasantly surprised to see the thing is still running.

Cheers

 

[Toni]

Well,thank''s for the replys!That''s exactly what I was loking for!
Dan,do you mean that you have 35 sec time before droping the colective in a 206???

Thank''s again

 

[Winnie]

I don''t think so!!!
It should not take less than 2 seconds from 100% to 60%, but then that is on the ground,
although the engine might fail "SLOWLY" you will start sinking soon, and the horn should come on fairly quick if you do not react!

 

[Dan]

Sorry for the confusion. No you don''t have 35 seconds to drop the collective if the engine fails.
It takes approximately 35 to 40 seconds to start a turbine engine to ground idle. So when one fails in flight at 1000 feet agl, you will be on the ground before you can get the engine back running again.

 

[Nomex]

Several years ago, a very experienced & cool-headed support pilot for Hayes lost his engine (206)at Harrison Lake in a hover with a long line & chokers at around 200'' AGL (steep slope) and (I could be off a bit), 2000 AGL the lake. He was able to avoid ground personnel, then pickle the load, stretch the glide to get over a small ridge downslope, call the barge to clear a landing area,then did an engine restart and got it going and flying just as he was about to start the auto flair, and was able to fly away.

Quite amazing, he also kept the mike keyed throughout and everyone on the ground heard him talk himself through the engine restart procedure. as I understand, they never determined what caused the flame-out.

Moral is to keep flying the machine all the way down and if you can attempt a restart WITHOUT compromising the auto, all the better!

 

[412driver]

the way i figure it, if you hear the horn dump the pole and leave the throttle alone. you can always roll off the throttle later. if you dump the pole you keep your rotor rpm''s up (VERY IMPORTANT) and then look for secondaries. you should be high enough from the ground to do this (hopefully).

if she is still running then just pull pitch and fly away....

 

[Oryxs]

Just my 2 cents worth but something alot of people forget is their own warning system, meaning their hearing. Lost one about 2 years ago and I actually heard the engine spool down. It''s going to get awfully quiet in there very quickly.

Fly safe and enjoy the summer

 

[412driver]

good point Oryxs. wasn''t there a case a few years back that had a 100 hour guy flying the top brass? he had a false indication and on the way down the guys could hear the turbine running but didn''t say anything and they ended up autoing into the water?

 

[Jammed left]

I know the story your thinking of 412. There was a great deal of pilot hours in the machine that ended up in the water. What happened was the cannon plug worked it's way off the n1 tach gene, and the horn went off - the pilot entered the auto - rolling the engine to idle as he did. The guy in the passenger seat (with many hours himself) saw the indications that the engine was running and asked the pilot to pull in some pitch. He did and the rotor started to droop - so down with the pole and they put it into the water - very nicely I'm told.

I think that they figured the pilot rolled to idle because that is what he did when he practice them annually - subsequently training pilots now roll the throttle off during recurrent for that company now. This also brings up a point with some new pilots who did training on r22 and 44's. During full ons, the pilot has to keep the throttle in the over travel position(past idle) to disengage the governer. I know a fella or two who have it engrained in their auto training to roll the throttle to idle. There should be some awareness of the potential to be in the situation where they've entered the auto, rolled to idle without really thinking about it - they you could find yourself in the same situation as our aforementioned wet ones, with a false engine out indication, the dials telling you that the stove is still on, but no useful power- and in the heat of the moment, it might not get sorted out until too late. Not sure if it has ever happened that way, but food for thought, no???!!

 

[Puddle Jumper]

Here''s one that I don''t fully understand...maybe some of you boys can help me figure it out. Supose you go flying and forget to turn on the generator and the battery voltage drops below 14 volts DC...the engine out horn should activate...why is this?.. I can''t remember!

 

[Cambox]

Mmmmmmmm......... Anyone think we''re going to feel a bit of yaw if the stove actually quits???



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