Jump to content

Hypothetical:Engine stuck on full throttle in flight

Recommended Posts

I was pondering a hypothetical scenario (that may very well have happened to someone) and how you could possibly deal with it..

Scenario: Full tank of fuel, not long taken off and engine goes full throttle, stays there and kill switch does not respond.

There are probably some models of motor that have a reachable cut out switch but I am assuming that if yours doesn't have that switch there are not many options other than -up!

Could this be considered a super rare occurrence?

Link to comment
Share on other sites

Interesting :)
I have a secondary kill switch (Bailey V2)
There are no "major" issues that would cause a panic response so I am guessing I would place myself within glide of my takeoff and attempt to reach the plug, if it was pre-igniting (still runs with the plug cap off)  or I couldn't reach the plug, then I would have the option to pull the "fuel level viewing tube" off and allow the fuel to drain out but I would be pretty reluctant because if it atomises and plumes in the drag-shadow, it might get to the exhaust (four stroke, very hot, a chance of spontaneous ignition)
I could attempt to pull the air filter off and block the intake (K&N cone type job)....
I might even be able to reach and pull the intake manifold vacuum line...

A full tank = four hours of flight on my machine (less at constant full chat) and I rarely take off without brimming it.... If all else fails, I think I would head for open airspace and allow it to climb, I'm assuming it would top out around 10,000ft and I am assuming cloud base would be below that so at least it would be nice and smooth even if its a tad cold :)

Link to comment
Share on other sites

Very good question that I’ve thought about before. A lot of fixed wing aircraft are set up so if the throttle cable fails, it goes into full revs as the idea is to stay in the air until you can flick off the fuel and land. The paramotor engines I have seen are the reverse, If the cable snaps on my mini plane, the engine goes to idle. However, it’s a very useful thing to think through.

Has this ever happened to anyone?

I doubt I could reach the spark plug cable but I’d try.. or pull the fuel line out of the tank.. could possibly get hold of the fuel line near the filter. Throwing reserve would bring you down but would be foolhardy. 

The main issue is altitude, I think I’d just enjoy a long flight and use big ears and B-line deflation if I needed to reduce altitude from time to time.. I’ve done b-line deflation in glider but never under power but i suspect it would be the easiest way of staying low, anyone here tried it? Anyone tried big ears under power? 

If you have trims, letting them out would reduce climb rate too..

Spiralling to reduce altitude under full power is unadvisable, too much g force, risk of black out or losing control of the glider getting locked in.

In conclusion, if I couldnt get the spark lead or fuel pipe, I’d style it out and reacquaint myself with b-line deflation technique..

Ps - choke on mini plane would prob kill engine or reduce power but mine is disconnected 😳

Edited by Patrick1
Link to comment
Share on other sites

I agree, just opem trimmers, full speedbar from time to time, big ears...ride it out.


I personally wouldn't go trying to reach behind into cage area...that area whilst engine is running is a bed of snakes!


Most engines have both ignition and kill switches...I think you have a pretty good chance of safely shutting down with these two alternatives.


Some engines has clear fuel primers that are easily within reach whilst strapped in. Perhaps one option might be to perforate/rip the primer so it sucks air thus starving engine of fuel?


If I were reaching around into cage, I would go for blocking the air filter intake...however both my paramotors are high hang point so the ability to move around in harness is extremely limited (On nirvana Rodeo virtually impossible)

I am not sure about bline stalls under full power, I'm of the opinion that could be catastrophically dangerous as I have lost control of a glider after it went parachutal  doing that once...it ended up a bed sheet beneath me and I missed falling into it by inches as I fell down though.


Safest is big ears, 360's, and wing over into 360 to minimise regain altitude as you exit wingover (the degree of wing over depends on experience and skill obviously). These manoeuvres are really only for short bursts to get rid of excessive height...you are gonna get pretty tired awful quickly if you tried to spend the entire 2 or more hours doing them,


Main thing is not panic and fly it out (keep the wing flying stable) staying well within your level of experience and skill. You are unlikely to die flying for 2 hours till fuel runs out, but you could easily die cocking up trying to pull plug, fuel line, or performing unstable descent techniques (high power bline stalls in my book are unstable and potentially very very dangerous)

Edited by adamjedgar
  • Like 1
Link to comment
Share on other sites

Could i also add to my above post, and this is something i believe incredibly important about such a scenario...

let's say it was possible to have a throttle get stuck wide open and one could not shut the engine down. Imagine if, in the process of trying to perform fairly risky height loss maneuvers (considering they would be under high power setting), what if something catastrophic happened with wing and one had to throw the reserve chute? The engine is still running under high power, and the reserve is deployed.. no way to shut the engine down,I could imagine that being a recipe for death!


has anyone ever tested a reserve throw whilst engine is producing near max power with the main canopy completely out of control? (i cant imagine anyone being game enough to even try)

Edited by adamjedgar
Link to comment
Share on other sites

Having read this I will be looking at my V3 and Moster setup to see how to have a secondary kill method.

My thoughts are probably back up kill by fuel so extend the fuel feed to a place where in the seat I can reach and pinch.

If the kill has failed potential is the pin on the coil has jumped off so a 2nd switch is not going to do a lot.

I´d also get to safe/normal cruse height and attempt kill as opposed to riding it out as chances are running the Moster or any other engine on full power for a complete tank is going to end badly anyhow as they are not normally running so hard so long.

I don´t want to fit a tap as potential for air to get in but i think with the throttle open it would not need a full pinch to kill the motor from fuel starvation.


Link to comment
Share on other sites

Having witnessed 2 motors stuck on full power,  I have a cord knotted and attached to my plug lead, threaded over the shoulder down the harness sleeve with a plastic ball for easy grab. Just pull and the cable will separate from plug cap. 


Edited by Graham
Link to comment
Share on other sites

Some followup as this got me thinking a lot.

My Parajet V3 and Moster 185 only has 1 kill switch so if the button fails there is no kill option.

2nd electrical kill is an option but I wanted a non electrical solution as I think electrical failure is more likely fatigue of connection at coil and 10 kill switches will not help here.

So fuel cutoff is my logic.

On my V3 there is a support bracket for the prime bulb and P-clip.

With the help of my son I did a simulated reach check to see if from normal hanging/seating position I could reach the fuel pipe to pinch off the fuel.

Original position was very hard to find from blind feel and at the limit of my reach.

I rotated the bulb support bracket about 25 deg and re-routed the throttle cable as it was very gently guiding the fuel pipe away from my reach.

The new unobstructed position leaves the final to carb fuel pipe a lazy radius that is easy to reach and either pinch off or worst case tear off.

I was very glad to hang test and see how hard it was to reach, mostly was a good test to know where to reach to as now its actually quite easy.




  • Thanks 1
Link to comment
Share on other sites

Also an option but another part added, removed parts never fail :) quote from FMEA manual.

Plug pull with panic is very probably going to work and I´m sure the pull will keep it clear of fast rotating bits, assumption being were on full power.

KISS says if you can use what is there already why not but absolutely would have gone that way rather than adding additional fuel pipe length. 

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.


  • Upcoming Events

    No upcoming events found
  • Create New...