Rough Running Engine
 

You are flying around on a nice VFR day and the engine suddenly starts to run roughly - what would you do?

Carb heat full / fuel pump on if you have one / change tanks if an option / start looking for a nice field /find it then see what else is happening with engine. Then use radio.

You can also check if the roughness goes away when running on just one magneto. But only after you've picked a field and informed ATC.

shut it down, use the other one!!:}

There was this single-engine fighter jet a few years ago who had a rough running engine. He declared a pan, got vectors back to the field and was then held up by ATC because there was a B-52 on final, also on a pan, "with one engine shutdown".

"Ah, yes, the dreaded seven-engine approach. I'll hold." was the dry response of the fighter pilot.

Carb Heat -- On immediately

Then check Primer Locked.

If engine getting rougher for a bit after carb heat applied, ice is likely. It should smooth out once ice melted.

Mixture depends on high you are and temperature. The last time I flew a C-172 in the winter, there was quite the nasty stumble arriving overhead the airport after a descent at lower revs. Carb heat made it go away:ok:

Fuel pump can help or make things worse -- keep an eye on fuel pressure if playing with it. Even better, know what the normal fuel pressure in various flight regimes should be.

If still no cure, try each mag as mentioned before.

Oil temperature/pressure, EGT, CHT may all have hints.

You land at the first airport from which your girlfriend can get a cheap airline back home :)

Seriously, it is system dependent. Pull out carb heat, mixture full rich (unless already at high altitude), pull alternate air (if fuel injected). Full pump ON. The rest depends on available engine instrumentation: EGTs, CHTs, fuel flow rate. There is even a failure mode on some Conti fuel servos which gives you a rich cut and the only way out is to lean drastically.

You have to know the plane and all its systems before you get airborne.

swear..........then do the same as everyone else!

You just made me realise again how long it's been since I flew the DA-40 TDI.

- Power lever MAX
- Switch from ECU Auto to ECU B
- Switch to alternate air intake

With the DA-40 there's even time to pull out the checklist AFTER your engine has failed :}

IAS - 75kt
Power Lever - MAX
Check Annunciator Panel
Check Ts & Ps
Check Fuel
Check Emerg. Fuel Xfer - Normal
Fuel Xfer Pump - On
ECU - ECU B
Engine Master OFF/ON
ECU Auto

Still no engine? Just mush down at 500ft/min :p

The answer really depends on the aircraft and the powerplant, and the circumstances. No matter what you're doing, if you're flying visually, once the engine starts running rough isn't the time to start deciding when and where to go. What to do is decided before you ever strap in for the flight, and where to go is a second-by-second decision you make every moment of the flight.

The year before last I experienced a rough engine in a single engine tailwheel airplane at about 300 AGL over a heavily wooded mountain forest area. I took steps to ensure the engine was running; made sure it had every chance to have fuel and spark by verifying the ignitors were on and the fuel boost pump was on. I pushed the speed lever (for that engine) up, and prepared to make a forced landing. the engine was surging badly, from idle to about 75% power. I followed a road off the mountain, keeping it under me until I reached a rural airport about ten miles away, where I landed.

About three months later I experienced another power loss in a similiar airplane at about 150' as I exited the bottom of a steep canyon, and made a forced landing on a hillside.

Be prepared, but do that preparation before you ever leave the ground. Then use that preparation every moment of every flight. The life you save, among others, will be your own.

Don't forget to look for a school to narrowly miss. The media will love you for it.

You are flying around on a nice VFR day and the engine suddenly starts to run roughly - what would you do?

First apply the POH actions for rough running engine on that type.

To answer further, need to know

What altitude

What is the fuel state

What track I am making good?

What is the wind direction/speed

What weather conditions (nice VFR day is pretty vague - if its -20 degrees it may skew the decision)

Over sea or land

If sea, are there ships nearby

What is the sea state

if land, what type of terrain

How close is nearest populated area

How near is nearest usable airfield?

Any physical signs of why engine rough - e.g. oil or smoke?

Depending on the answers to the above, I might consider a number of decisions

Well, at the very least I think you ought to tell one of the cabin crew when you order your next GnT ... :cool:

Thanks for all the fantastic replies guys - what a lot of experience there is here! Final 3 Greens asks a lot of relevant questions and having applied the POH actions for rough running engine on that type it then depends on the situation.

I am assuming we have a single engined aircraft but another consideration would be to point the aircraft towards the nearest suitable aerodrome and gain height if possible. When overhead said aerodrome close the throttle and perform a forced landing procedure. If the engine is running rough it might quit completely whilst performing a normal join where you might not be within gliding distance of the runway.

Slightly related but slightly off the thread
 

There was an interesting article in the US AOPA mag about Engine Failure At Take Off situations. It could be applied to EF at any altitude but likely your speed will be higher.

The first thing that should come as an automatic response is to unload the wings.....push forward hard. The article makes a point of stating how much you actually have to push, and the amount of horizon which fills the screen - it varies for each aeroplane but rule of thumb is that you go from 2 thirds sky filling the screen (on climb out) to 2 thirds ground filling the screen (at best glide).

The reasons for this are (amongst others)
a) when the wings are unloaded in the push over, nothing bad like stall / spin can happen and it gives some extra time to think about things. A pilot faced with EFATO is likely to be caught off guard and an automatic response like this could save a life or two.
b) You need to increase airspeed by sacrificing height, there is no other way around ;)

Good article......

I notice not many of you mention a quick call to ATC!! even if you are not talking to ATC how about 7700 on the transponder, at least then when you drift down below radar coverage your last known position will be left on any radar that was seeing you!! Little point in making a safe survivable landing over hostile terrain ( The Scottish highlands) only to die of exposure on the top of a 3000ft mountain!!

In my case it was carry out the normal checks and divert to the nearest a/d. I was en route Popham to Henstridge and talking to London Inf so I told them what was happening and that I was diverting to Compton Abbas. They asked if I wished to declare an emergency, which I declined. CA was in sight so I switched to them explained the problem and they cleared me straight in for an uneventful landing.

The problem was a drop in RPM and an increase in vibration. Drained the gascolator to check for water and/or debris. Unable to reproduce the problem on the ground despite extensive checks so eventually took off without incident for return to Popham.

About 5 mins after departure it happened again. I established that a slight power reduction caused it to go away and opening it wide caused it to reappear after a minute or two. With Bowerchalke, Old Sarum, Middle Wallop and Chilbolton all along my track plus plenty of fields it wasn't a crisis.

After about 3 days and lots of running the engineers ran it to ground as a valve guide breaking up. Most of the time the valve seated fine and compressions were normal but clearly at high power settings it was vibrating out of alignment, the valve wasn't seating properly and she was only running on 3 cylinders.

Your question doesn't give enough information for a sensible answer. Running rough? The Beagle Pup I used to fly did that. The answer was simply to turn it the right way up again, whereupon the problem went away.:E

Deliberately so, my dear chap!

The only time so far I've had an engine failure I solved it in two seconds...

I'd turned the fuel to OFF instead of Right.

Which is why PA38s have a button you have to push to turn the fuel off - otherwise it will only go on Right or Left. A feature which long ago should have found its way into the PA28, if you ask me.

I nearly had a heart attack, though.

Tim