Monday we talked about the importance of trimming the elevator for stability. Today with an engine failure, we must trim the rudder for lateral stability.
The key to flying the Boeing on a single engine is trim and power application.
With a single engine—
More power requires more trim.
Less power requires lest trim.
The trick is to get your power set, and make the smallest changes possible, creating the most stability. Reducing the possibility of instability.
A change in power creates instability with an engine failure.
When you lose your engine, climb to your company’s cleanup altitude while performing the procedures and checklist items then put the autopilot on.
The autopilot serves two functions:
1. Provides you more time to manage the situation.
2. It helps to determine “how much” and “which direction” for the rudder-trim.
In the traffic pattern, or the local area—since you’ll be vectored for a return to landing—get your plane to the minimum clean maneuvering speed.
With the autopilot on, the control yoke will tell you if you need more trim, or have too much trim, by pointing in the direction the rudder trim needs to go. The airplane is using the ailerons to help her fly straight. So, if the control yoke in cocked to the left…reach down and tweak the ruder toward the left.
Yes… the same direction the ailerons are pointing. As you apply rudder… the control yoke will move to a neutral position.
If you have the autopilot on and the control yoke are showing straight, you have the exact amount of rudder necessary for the given speed. What speed? Minimum clean maneuvering speed. You want to be at the slowest speed possible clean.
Flying the approach…
This is where new pilots learning how to fly with an engine failure have problems. Finding the right amount of power for the speed, while maintaining directional control with the correct amount of rudder.
Remember when I said, “with a single engine: More power requires more trim. Less power requires lest trim?”
What would happen if you could fly the approach and not change your power? You would never need to change your rudder trim. Think about that from a stability point.
So… here is what you’re going to do the next time you fly a single engine:
· Get her clean.
· Get her on speed.
· Autopilot on.
· Set the rudder trim.
Now you can take the autopilot off … because you know how those sim instructors are, they’ll just fail it anyway… and you will be in trim.
The trick is staying in trim, and this is how you do it:
Yes… you’ll use the drag created by extending your flaps and gear to slow your plane. Flaps 1, she will slow. You maintain level flight, and put out drag. Plan your profile so your gear will come down as you’re about to capture the glideslope. This will help keep you on speed. You will be surprised how close to the actual speed this process will keep you without ever touching your power.
There will be a point you’ll have to bring back the power just a bit to maintain your final speed and consequently squeak off a little rudder at the same time.
Visualize this: Same foot same engine. More power = more foot. Now… if you’re reducing the power you will technically need less foot. But you have the trim set, you’re on final, do you really need to take out what you have? Not really. I always like to press a little opposite rudder. Same thing, right?
Right rudder down means left rudder back. Therefore if I want the right rudder to come back— less trim—the left rudder must go forward. By not messing with my rudder trim from clean maneuvering, this also helps me to go back to that configuration on the single engine missed.
As you apply the thrust lever for the missed approach, apply the rudder at the same rate. Imagine there is a bar attached between your hand and your foot. Push them forward at the same time… at the same rate.
You have two choices here. Add more rudder trim for takeoff power, or use your foot for the rudder, and as the speed increases and power comes back… so does your foot. Remember what we started with? The plane was trimmed for minimum clean maneuvering speed. That’s where you’re headed for the next approach.
I like to make things simple. Try this in the simulator and see how easy it works. And if you experience an engine failure in the airplane… well, you’ll be surprised how easy it is to control the plane.
Enjoy the journey!
Wow, that was a fantastic explanation, Karlene. I almost felt like I could do it, and I've never flown any plane. (I guess it's better if actual pilots do this.) Makes me think of an exciting scene in a book. Hmmm.ReplyDelete
I love Boeings so much. I would love to learn to fly one someday.ReplyDelete
When would aileron trim be used?ReplyDelete
Karlene, thank you so much! What a great post! I think you are right on track. I think 2 of the best tips are to try to avoid thrust changes as much as possible, and to use gear and flaps to slow rather than changing the thrust setting. I really appreciate you posting this, and I look forward to trying it out soon! I believe my sim tomorrow night has single-engine approaches.ReplyDelete
Linda... I'm thinking this could be a scene... yes. Coming soon.ReplyDelete
Christine, you will fly a Boeing one day. Keep believing.ReplyDelete
Cockpit... Aileron trim? Never. Okay... never say never. But we never used it because it causes more problem than not.ReplyDelete
Really... when you would use it if for some reason you have to put in a lot of aileron and hold it. The trim should relieve that pressure. But when would you do that? You wouldn't. You just fly what you need. That might be a better question for Boeing. Why did they give us something we don't use?
Thanks for a great question.
Daniel, Everything comes in perfect timing... I'm glad I could help. Let me know how it goes. I know you're going to do great. Remember to have fun!ReplyDelete
Thank you again Karlene! In regards to aileron trim, we had a dual hydraulic system failure in the simulator. It had a lot of other associated problems that needed to be dealt with and having use of an autopilot was very helpful. But it kicked off pretty quickly. I realized it was because the loads on it were too much, put in some aileron trim to make it happy, and it worked perfectly from there forward. I don't know if this is how the real airplane would act or not...ReplyDelete
Yes that question was for Boeing planes. I know Airbus does not have aileron trim.ReplyDelete
Daniel, Excellent on the use of Aileron trim. And YES... this "IS" how the plane works in real life. The thing we need to remember is that trim is used to make our life easier. And the autopilot is only so strong.ReplyDelete
I'm sure there could more emergency abnormals that aileron trim might help too. You know... that might be a good rule... if the autopilot won't hold, ask yourself why? She could just be out of her trim tolerance... rudder or aileron.
Which brings up a good point. The rudder trim needs to be close or the same thing will happen with the autopilot... it won't hold.
Cockpit, Yes... the Airbus is in a league all her own.ReplyDelete
on airbus planes, if you had the autopilot on with an engine failure, how would you know whether you need to add more trim or less trim, since airbus planes don't have a yoke?ReplyDelete
On the Boeing, the autopilot will use the ailerons to counteract the incorrect rudder position. We can see this. And, we can trim the rudder even with the autopilot on.
On the Airbus, the only time we can trim is if we are manually flying the plane... No autopilot.
When an autopilot is on, the trim knob is deactivated and the FMGEC computes the rudder trim required and the plane does it itself. She's smart.
when applying rudder trim, would you apply it in small increments?ReplyDelete
Small increments is a good way to do it until you get what you need.ReplyDelete