Question: If for arguments sake the elevator cable

[Messerschmitt Man]

snapped during flight in say a Cherokee would that render the aircraft uncontrollable about the lateral axis? Or would there be a degree of pitch control through the trim?

My guess is the rudder would stay in the full nose up or nose down position & no trim input would change that? and the only real chance of pitch control would be through throttle inputs (less throttle = lower nose attitude & vice versa).

Your thoughts please. :)

[oldHooker]

snapped during flight in say a Cherokee would that render the aircraft uncontrollable about the lateral axis? Or would there be a degree of pitch control through the trim?

My guess is the rudder would stay in the full nose up or nose down position & no trim input would change that? and the only real chance of pitch control would be through throttle inputs (less throttle = lower nose attitude & vice versa).

Your thoughts please. :)



In a light aircraft, as long as you maintain speed, some pitch control can be maintained using the Elevator trim, but it would not be sufficient to Flare the aircraft for landing. About the only option one would have is to attempt a high speed landing where decent would be minimized by the speed..... but then there's the issue of having enough room to perform such a maneuver! Maybe over a dry lake bed, maybe?

**The "Rudder" has nothing to do with Pitch control**

Unless one has their sh*t wired extrememly tight, and is blessed with an exceptional amount of luck, chances are they wouldn't walk away from it.

Take care,
Frank

[MCM]

I've seen a trim-only landing on a seminole when they lost control over the elevator for some reason (I can't remember why).

All a bit of a non event... they trimmed the aircraft at a slowish speed for a low rate of descent for final, and then just quickly run a bit more in for a "flare". The throttle provides significant nose up/down moment on light aircraft.

Reasonably firm landing but nothing worse than I usually do when everything was normal *grin*.

Haven't tried it personally though!

[Jet-fighters.Net]

Sean Tucker lost control of his elevator in April 06 and used the elevator trim to control the A/C to get it to a safe area to bail out.

Here is the NTSB findings on that accident.

http://ntsb.gov/ntsb/brief2.asp?ev_id=20060405X00398&ntsbno=DFW06LA094&akey=1

[Dmmoore]

Many trim only landings have been made over the years. A few were actually accomplished because the primary control cables had sheared.

I used to practice a trim only landings in C-150's and C-172's. It works well with a 0 flap approach, speed 80 knots all the way to the runway. Fly it on at 100 - 200 FPM rate of descent, no flair, ground effect will cushion the touch down, throttle to idle, normal braking. Distance for the 150 is about 1500 feet. A little more for the 172.

In the 80's a Reeve Aleutian L-188 Electra lost #4 prop. It sliced through the fuselage severing ALL primary flight controls and ALL engine controls. The Aircraft was on a flight fro Cold Bay (PACD / CDB) to Seattle (KSEA / SEA) and diverted to ANC. I witnessed the landing. The crew landed the aircraft by shutting down engines as they approached ANC. Made a low (approach with #2 and 3 providing power) to prove they had enough control to attempt a runway landing. If not, they were planning on landing on the mud flats in Cook Inlet. Beautiful landing using only trim. The aircraft ran off the runway at the end of the roll out. No injuries.

Don
Refugee from ADC

[Half Bottle]

I used to practice a trim only landings in C-150's and C-172's. It works well with a 0 flap approach, speed 80 knots all the way to the runway. Fly it on at 100 - 200 FPM rate of descent, no flair, ground effect will cushion the touch down, throttle to idle, normal braking. Distance for the 150 is about 1500 feet. A little more for the 172.

Refugee from ADC
Interesting, Don, thanks. Throttle to idle just before touchdown or just after?

[Dmmoore]

Interesting, Don, thanks. Throttle to idle just before touchdown or just after?

At touchdown.
A little before and the nose will drop.
A little after and you will balloon back into the air.
Also, roll the trim forward as soon after touchdown as possible.

We used to practice rudder and elevator trim only landings. Not as pretty but also possible to land (C-150, C-172, L-188) with no ailerons or primary elevator control.

The Reeve L-188 did not have primary rudder control. The F/O operated the trim, Captain operated the elevator trim, S/O took care of what power plants they had operating.
One of the best examples of CRM I've ever witnessed.

[JordanD]

This procedure is actually listed in the emergency section of the 172S POH.
It says to trim for level flight at 65 knots with the flaps at 20 degrees, then not to touch the trim, using only power to control the glide. At the flare the nose may fall as a result of the reduction in power, so they say to apply full nose up trim before touchdown.
Not that I'd necessarily want to try this, but it's better than them saying "oh well, you're pretty much f**ked. :razz:
I wonder what you'd do in a T-tail.

[474218]

Shouldn't the elevator be balanced? A balanced control surface should go to the aerodynamically faired position. In the aerodynamically faired position it does not provide control but will provide stability.

[Dmmoore]

Shouldn't the elevator be balanced? A balanced control surface should go to the aerodynamically faired position. In the aerodynamically faired position it does not provide control but will provide stability.

A "BALANCED" flight control is balanced to prevent control surface flutter. The trim setting determines where it rides.

On and aircraft with stabilizer trim, the elevator always fairs with the stabilizer unless the pilot or auto flight system moves it.

[tds]

Don... going back to your emergency drills, is there any truth in the rumour that you can exercise directional 'control' of a C152 by coordinated use of the doors?

[Dmmoore]

Don... going back to your emergency drills, is there any truth in the rumour that you can exercise directional 'control' of a C152 by coordinated use of the doors?

You can. But I never gad the guts to try a landing using only the doors for directional control.

[tds]

You can. But I never gad the guts to try a landing using only the doors for directional control.Wow... so you could lose all primary flight control linkages, and still be able to attempt a controlled landing. Nice.

[Dmmoore]

Wow... so you could lose all primary flight control linkages, and still be able to attempt a controlled landing. Nice.

You had better be an octopus if you lost all primary flight controls. :smilewin:

[tds]

You had better be an octopus if you lost all primary flight controls. :smilewin:Yeah, I guess trim, engine controls and both doors on approach might be considered a 'high workload' situation for a solo pilot. :)

Good CRM exercise with two, maybe!

[AVIATIONFASCINATION]

That would be interesting to see.

Anyone know of a simulator that has doors?

[3WE]

You had better be an octopus if you lost all primary flight controls. :smilewin:Two items:

1) The trim, throttle and pedal landing is something that I've heard talked about LOTS, and I imagine instructors do it a lot too. My instructor tried it one day, but winds were a bit gusty and he wound up grabbing the yoke at the last minute (Cessna is a wonderful, forgiving plane, except for the nosewheel, which doesn't break up and die, but get's this anoying wiggle!)

2) Light Single Cessnas- outstanding planes- they don't even need controls, you can do it all with doors, trim wheels and throttles....no runway...no problem, drop ALL the flaps bleed ALL the speed and with a little luck you'll be stuck hanging alive in the trees, hoping the limbs don't break and kill you in the fall...All that great stuff and then we have the cirrus and it's ballistic chute...

[Dmmoore]

Two items:

1) The trim, throttle and pedal landing is something that I've heard talked about LOTS, and I imagine instructors do it a lot too. My instructor tried it one day, but winds were a bit gusty and he wound up grabbing the yoke at the last minute (Cessna is a wonderful, forgiving plane, except for the nosewheel, which doesn't break up and die, but get's this anoying wiggle!)

Light and variable winds are a prerequisite. :clap:

2) Light Single Cessnas- outstanding planes- they don't even need controls, you can do it all with doors, trim wheels and throttles....no runway...no problem, drop ALL the flaps bleed ALL the speed and with a little luck you'll be stuck hanging alive in the trees, hoping the limbs don't break and kill you in the fall...All that great stuff and then we have the cirrus and it's ballistic chute...

Only works if you have very good insurance and your intent is not to reuse the aircraft without a rebuild. :p

[Gabriel]

Someone asked about T tails?

Well, the Tomahawk has a quite rare trim system.
No trim tab. No movable stabilizer.
Springs.
I really don't know what practical consequences would that have from a pilot's point of view. I've flown the C-152 several times (trim tab type) and found no practical difference trim wise.

A "cables failed" flight is the same than a hands-off-yoke flight. So it can be practiced without severing any cable.

I've tried a trim approach in the Tomahawk a couple of times. It was relatively easy to use it for the approach and to coordinate with the throttle to achive the desired speed and descent rate. However, as the response with the trim is slow (several turn movements to move the yoke an inch), the flare is quite hard to do it at the right time and right ammount. With the yoke you pull it to raise the noose and then push a bit (or release some pressure) to prevent balooning up. It's a quick move, impossible to do with the trim. I always ended grabbing the yoke for the flare.

I've never tried the 100fpm descent. I guess that would work (if there are no obstacles in the approach path, or if there is a long enough runway to aim to the midpoint).

However, in general the actuation of the elevator is via two pull cables. Chances of both cables being cut or lose are small (unless something like a prop blade cuts them).

If only one cable fails, then you still have full authority in one direction. Just apply a good bunch of trim in the opposite direction. You'll have to keep a constant push or pull on the yoke, but increasing ro releasing the pressure will easily control the pitch as desired. It's not like with everything Ok, but it's really easy, just a discomfort maybe. I've done it.

And since I'm new in this forum, maybe someone at JP doesn't know what a Tomahawk is (I've made sure that evrybody at AD knew).

The Tomahawk is the Piper PA-38-112. The one in my avatar.

[Gabriel]

And one more thing.

Some years ago in what was my home airfield there was a mid-air. A Cessna 172 had taken off, made a 180 and was climbing, when its prop struck the tail boom of a C-152 that was in the downwind leg for landing.

The prop of the 172 was damaged and they lost the engine power (don't know why). They made it back for a deadstick landing on the runway.

The 152 got the elevator cables and trim rod severed. No pitch control, primary or secondary.

The 152 happened to result "naturally" ballanced for a speed that was beyond what the engine was capable to sustain in level flight. So they descended at full trhottle and high speed, but at least the descent was shallow. They crash-landed in a farm. The plane was absolutely destroyed but, amazingly, the 2 occupants escaped badly hurt but alive and eventually recovered. Based on comment from people who talked to them, they didn't thought of shifting weight. They could have slided the seats all the way back, even one of them could have jumped back to the baggage compartment. I don't know if that would have worked, but I would have tried.

[3WE]

They could have slided the seats all the way back, even one of them could have jumped back to the baggage compartment. I don't know if that would have worked, but I would have tried.I don't know if I'd think of that or not.

Also, seat sliding sounds good, but to "hop in the back" would require unbuckling the seat belt which we know from the automobile world would likely reduce the survival odds for that person.

[RadarContactLost]

Gab,

Does the T-hawk have a "normal" trim wheel or is it still the crank on the overhead?

[JordanD]

Two items:
ballistic chute...
Ah yes the "ZOMG IM JUST GONNA SIT HERE AND SHIT MY PANTS chute" :razz: Honestly in some cases I'd rather make a forced landing than deploy that thing. There was a guy breaking his back pretty badly and ending up in the water unconcious after an emergency landing with the chute deployed. Kind of off topic but does anybody know what happens if the ballistic chute is deployed above the recommended speed?

[Gabriel]

Gab,

Does the T-hawk have a "normal" trim wheel or is it still the crank on the overhead?
I couldn't find a suitable picture.
But in the picture below you can see the flaps lever between the seats.
If you could look a little more down next to the root of the flap lever, you'd see a typical trim weel and trim index with an "N" marked for "neutral".
http://www.pilotfriend.com/training/flight_training/images2/15.jpg

[Dmmoore]

Ah yes the "ZOMG IM JUST GONNA SIT HERE AND SHIT MY PANTS chute" :razz: Honestly in some cases I'd rather make a forced landing than deploy that thing. There was a guy breaking his back pretty badly and ending up in the water unconcious after an emergency landing with the chute deployed. Kind of off topic but does anybody know what happens if the ballistic chute is deployed above the recommended speed?

:topicoff: But as long as we don't hijack the thread. :p

I'm one of those that think the ballistic parachute may have uses in specific circumstances. However I wouldn't EVER put an aircraft into a position where I would need the thing.

I'm sure the chute would deploy okay if it were deployed 10% over the maximum speed but above that you have a serious risk of damage to the chute and or rigging. Damage to these increases the speed at which the aircraft smacks the ground.