Broken Throttle Cable

[Flocker]

My CFI threw me a curve ball this weekend. Here's the scenario...

Broken throttle cable on downwind. Throttle stuck in the full position. (Apparently this is the default position with a broken cable) Now land the plane. Before I know it we're at 100kts and approaching the Base turn...

Before I post the recommended solution to the problem, has anyone else trained for this one? Has this ever actually happened to anyone?

[MrMorden]

My CFI threw me a curve ball this weekend. Here's the scenario...

Broken throttle cable on downwind. Throttle stuck in the full position. (Apparently this is the default position with a broken cable) Now land the plane. Before I know it we're at 100kts and approaching the Base turn...

Before I post the recommended solution to the problem, has anyone else trained for this one? Has this ever actually happened to anyone?

Fun! I'd say set up to where you know the field is made with extra altitude, shut off the engine and then land using flaps and/or slip (or even S-turns on final) as needed to get down.

[Wm.Ince]

My CFI threw me a curve ball this weekend. Here's the scenario...

Broken throttle cable on downwind. Throttle stuck in the full position. (Apparently this is the default position with a broken cable) Now land the plane. Before I know it we're at 100kts and approaching the Base turn...

Before I post the recommended solution to the problem, has anyone else trained for this one? Has this ever actually happened to anyone?

First off . . . keep flying the airplane!
Too much power? So what's the problem. Usually, in an emergency scenario . . . there is not enough of it. In airplanes and boats . . is there ever?

I would declare an emergency, divert to an airport with plenty of runway available.
Set up for an extended, long final . . . when landing is assured . . . give yourself an engine failure and land.

Submit a NASA report within 24 hours.

[CTLSi]

......

[drseti]

I would declare an emergency, divert to an airport with plenty of runway available.
Set up for an extended, long final . . . when landing is assured . . . give yourself an engine failure and land.

Submit a NASA report within 24 hours.

That's pretty much what I did about 30 years ago, when I had pretty much that scenario in a Beechcraft.

Dual XC to the restaurant at Harris Ranch CA (short strip) with my ex-wife in left seat. She had just transferred control to me for landing, and I had been retarding throttle to land when power stuck at about 20 inches manifold pressure. So, partial power when the throttle cable broke (fuel injection system didn't have springs like the Rotax does, to take it to full power). Too much power to land, and too little to do a normal go-around. So, I confirmed "my airplane," climbed out as best I could (anemic climb performance), raised gear and flaps when I had a positive rate of climb, and turned toward Lemore Naval Air Station's twin 10,000 foot runways. Squawked 7700, and by the time my student/spouse got the comm freq changed to 121.5, Lemore was calling us! Declared an emergency, and they cleared us to land, #1 for any runway.

I set up a long final, descended at well above gear extension speed, pulled idle cutoff when over the pavement, raised nose to slow it down to gear extension speed, dropped gear, which slowed us down further to flap extension speed, and then did a normal full-flap landing (still less than halfway down the runway).

I did indeed file an ASRS report, just for good measure. The Navy hospitality was great. I wrote the incident up in two chapters of my book "Winging It With Dr. Paul" (now long out of print). Excerpts at: http://avsport.org/publicat/nonfict/goaround.htm and http://avsport.org/publicat/nonfict/navy.htm

[CTLSi]

......

[CharlieTango]

Generally the key ingredient in a dead stick landing is the slip. If the runway is extremely long it becomes unimportant.

With power on approaches and landings we are pretty good making the runway every time. Unless we coast in we can adjust for being short by adding power and for being long by subtracting power. In a dead-stick landing we can't do that so we substitute a slip for the throttle as a control that we can adjust for landing both long and short.

We use an aiming point 1/3 of the way down the runway to ensure that we are not short.
We use enough slip to bring that aiming point to the needed touch down zone. Much like the throttle we can use the slip to continually adjust (longer or shorter) our aiming point.

Flaps are useful to do all of this at a slower speed and with a better view but the slip is needed to adjust for your imperfect judgement as well as you initially long glide.

[FastEddieB]

I would declare an emergency, divert to an airport with plenty of runway available.
Set up for an extended, long final . . . when landing is assured . . . give yourself an engine failure and land.

My only quibble is the "extended, long final" part.

In my experience, pilots have a very hard time judging their glide angle on long straight-ins. They often seem unable to discern way too high from way too low.

My advice would be to maneuver so one could cut power in a spot so as to arrive abeam the numbers of a long runway at traffic pattern altitude at one's normal speed for that position. That's a perspective and a position most pilots are more comfortable with than a long straight in. Then aim for a spot about half way down the runway, assuming it's long enough.

Should be familiar and a piece of cake!

But whatever works!

[SportPilot]

.......

[Flocker]

In a SkyCatcher, you can probably use the mixture to cut the engine in and out without shutting the engine down.

That's exactly what we did. First step was to pitch up and get the airspeed below 70 kts. Once under 70 kts, add full flaps. Then lean the mixture to the point where the engine is barely running. The mixture knob essentially became the throttle. We didn't actually land doing this, but it's good to know it can be done in an emergency.

[3Dreaming]

In a SkyCatcher, you can probably use the mixture to cut the engine in and out without shutting the engine down.

That's exactly what we did. First step was to pitch up and get the airspeed below 70 kts. Once under 70 kts, add full flaps. Then lean the mixture to the point where the engine is barely running. The mixture knob essentially became the throttle. We didn't actually land doing this, but it's good to know it can be done in an emergency.

I think like a mechanic as well as a pilot. In a real emergency I would have no problem doing this. In practice I have a real issue with running the engine in a lean condition for an extended period of time. It could possibly do damage to the engine. I know I wouldn't want an instructor doing that in my aircraft.

[drseti]

I was thinking exactly the same thing, Tom, but you beat me to the punch. Here's a technical explanation for those not familiar:

In engines with manual mixture control, such as the O200 in the Skycatcher, leaning the mixture raises cylinder head and exhaust gas temperatures. We use this to advantage in the event of a lead-fouled spark plug (usually detected during the mag check at runup). You maintain runup power and pull back on the mixture until the engine just begins to falter, run it there for a couple of minutes, and (with luck) the extra combustion chamber heat vaporizes the lead fouling the plug. Then, push mixture full rich, and repet the mag check. Quite often, you've cured the problem.

So, this shows that an excessively lean mixture raises the temperature in the combustion chamber. If you do this in flight, for extended periods of time. You stand a pretty good chance of burning an exhaust valve. In an emergency, that's the least of your worries. But I wouldn't recommend this as a training exercise!

Note that none of this applies with a Rotax engine, which has self-compensating carbs and no mixture control.

[Merlinspop]

....In engines with manual mixture control, such as the O200 in the Skycatcher, leaning the mixture raises cylinder head and exhaust gas temperatures. ..... But I wouldn't recommend this as a training exercise!

Or it might stop being an exercise and become an (expensive and wholly avoidable) emergency.

Note that none of this applies with a Rotax engine, which has self-compensating carbs and no mixture control.

Which is what had me confused about Flocker's 'solution' until I remembered he also flies a Skycatcher.

[Flocker]

In a SkyCatcher, you can probably use the mixture to cut the engine in and out without shutting the engine down.

That's exactly what we did. First step was to pitch up and get the airspeed below 70 kts. Once under 70 kts, add full flaps. Then lean the mixture to the point where the engine is barely running. The mixture knob essentially became the throttle. We didn't actually land doing this, but it's good to know it can be done in an emergency.

I think like a mechanic as well as a pilot. In a real emergency I would have no problem doing this. In practice I have a real issue with running the engine in a lean condition for an extended period of time. It could possibly do damage to the engine. I know I wouldn't want an instructor doing that in my aircraft.

For what it's worth, it was not done for an extended period of time. Only for a brief moment to illustrate the procedure.

[designrs]

We use an aiming point 1/3 of the way down the runway to ensure that we are not short.
We use enough slip to bring that aiming point to the needed touch down zone. Much like the throttle we can use the slip to continually adjust (longer or shorter) our aiming point.

Flaps are useful to do all of this at a slower speed and with a better view but the slip is needed to adjust for your imperfect judgement as well as you initially long glide.

Excellent. I want to practice this for emergency landings, but also to get more proficient at gliding in.