Crosswind Landings in the BE76

[Pole Hill]

Hi,
I didn't know where to put this question, so I'd thought I'd try here!
I'm currently doing the MEP rating in the BE76 Duchess. But I am finding crosswind landings quite a challenge, although I've never had a problem when flying light singles. I use the cross controls technique.
I can't quite remember exactly what happened on the last flight, but with a 20kt crosswind (from the left), it felt like there wasn't enough rudder authority when I wanted to 'kick it straight' and put the wing down into wind. I was landing asymmetric, so had a bit of left rudder trim in, but I was pressing really hard on the pedal! I was using full flap.
What could be the possible cause? The demonstrated crosswind limit is 25kts for the BE76.
Thanks,
POL

[BlueRobin]

Do both engines on the Duchess go the same way? Add their torque to a left-quartering wind and I wouldn't be surprised if a significant push is required.

[Jannik23]

I wouldt use full flaps on a crosswind like that - try less flaps

Jannik

[speedrestriction]

A forward C of G will noticably increase the forces required to obtain large rudder (and elevator) deflections. This often happens on training flights with two bodies up the front and nobody in the back.

You might get more info in the Tech Log forum.

SR

[Pole Hill]

Thank you all for your replies :ok:
claycomm: Thanks for that, I'll keep that in mind for the next time, and see how it works out.
BlueRobin: No, they are counter rotating.
Jannik23: Good point, thats what I normally do on the singles, I'll try flapless next time.
speedrestriction: Thats an interesting point. The rudder will be more effective though with a forward C of G due to rudder having a larger moment arm, so this would work in my favour.
POL :)

[Keygrip]

Land on the other end and have the cross wind from the other side?

[NavPilot]

The full flap, I my opinion, could be a real challenge. I'd try a partial flap...not essentially a flapless.

[silverknapper]

Yeah agree with above. 20 knots must be nearing limit of rudder authority. I was always taught not to use the last stage of flap if I was asymmetric. Less drag will mean less power needed all the way down leading to less rudder needed to counteract the yaw from live engine. Also less trim changes below ACH when you have enough to think about.

[speedrestriction]

The rudder will be more effective though with a forward C of G due to rudder having a larger moment arm, so this would work in my favour.

True, it will be more effective, but that isn't much use if it is too difficult to get the pedal all the way down. I found out the hard way. When you come to the MEIR the forward C of G helps makes the airways and approaches a doddle, but just wait for the assymetric go around.......I was walking crooked for a week!!

SR

[NavPilot]

but just wait for the assymetric go around.......I was walking crooked for a week!!
SR

SR
:ooh: ;) Was that on a duchess?

[Pole Hill]

NavPilot & silverknapper: I'll put your point accross to my instuctor when I next see him, it makes more sense to only use partial flap... :)
speedrestriction: I see what you mean. :ok: Oh, and the asymmetric go around, with 3 on board, 1hr out of the fuel tanks and on a hot summers day, very interesting.
Many thanks,
POL

[speedrestriction]

NavPilot: Seneca.

SR

[Oktas8]

Pole Hill - am I too late to respond? I was mindlessly browsing and saw your post!

I second KeyGrip's suggestion - with left rudder trim applied due to a failed engine, you would need right rudder to keep straight in the flare. You need even more right rudder if there is a crosswind from the left. Might explain the high rudder forces you experienced.

Couple of people above have mentioned running out of rudder authority in a crosswind landing. Not a likely scenario, as most light aircraft (and all twins) have huge rudder authority. Running out of aileron authority is much more likely. The cure is easy - land flapless at a higher speed, giving greater authority to your ailerons. But that isn't your problem I suppose...

Cheers,
O8

[kala87]

Pole Hill:

Also did my MEIR in Duchess. I used to find that in a x-wind (with both motors running or assymetric), the best technique was to use quite a lot of into-wind aileron just before touchdown. Counter the tendency to turn into-wind by using a much opposite rudder as you need. It can be a bit of a juggling act for a few seconds getting the right balance between amount of rudder vs amount of aileron, all the time keeping the aircraft aligned with the rwy centreline. The into-wind main wheel would usually touch down a second or two before the other wheel, but that's normal. I don't recall ever running out of rudder authority, and I never grazed a prop (so far!) Has anyone out there actually bent a prop on a light twin using this method?? In 20 kts of direct x-wind, less then full flap is probably a good idea.

[Pole Hill]

Oktas8: Absolutely agree, land from the other end. The problem is that the airfield is busy with GA and airline traffic, so I wouldn't be able to do that. Its something to keep in mind though in the event of an approach with a real engine failure and a significant crosswind component. Flapless or partial flap seems to be the most appropriate configuration.
kala87: Ok, I'll bear that mind. Now you mention it, I don't think that I've been putting in enough aileron either. My whole technique needs sorting me thinks :O
I'll get it right eventually!
Many thanks,
POL

[Piltdown Man]

Land into wind wheel first, then the other one followed by the one at the front. Don't bother with the rinky-dink, time-it-to-the-millisecond malarky of de-crabbing. And a question for you:- Is the crosswind limit you quoted valid for single engine!

[Jimmy The Big Greek]

I have 500 hours in the dutchess and I must say that it has good crosswind landing performance. I find it much easier to to land the dutchess then the C-172 in a crosswind.

I use a combination of the crab and cross-control. (crab in the approach crossed at the last part of the landing).

The dutchess is a very stable aircraft sometimes when I was experiencing strong crosswind or if I was heavy I used only 10 degrees of flaps or no flaps. This will increas the aircrafts responsivnes. Another trick that you have to try is to have a little bit of power during the flare (the throttle just about 2-3 cm from idle) and close the throttle at the last part of the flare, if you try this youre landing will be perfect and you also increase a little bit of rudder effectivness.

The dutchess is a wonderfull aircraft with a little bit experience you will love it.

[pushapproved]

When you go below ACA/H, i.e. you're commited to a landing, you could try moving the rudder trim towards neutral, this will reduce the force required by your leg in the flare/hold off...

[Pole Hill]

Piltdown Man: Good point. Thats something that I have totally forgot about. :O
Jimmy The Big Greek: I love the Duchess already! Out of curiosity, with no significant crosswind, all engines, what speeds do you use for the approach with flaps? I use 85kt final and 80kt threshold for all engines and asymmetric. I find that by using these speeds, the aircraft tends to float a little before the nose can be gently raised as the speed decays. I think that this was my problem, while the aircraft was floating for them few seconds, I was battling with the gusting crosswind.
pushapproved: I do this already, though I probably didn't take enough trim off in the flight that I described in my first post, but thanks for the tip anyway :ok:
Thanks,
POL

[Jimmy The Big Greek]

The speeds you are using are ok for single-engine and normal operation (blue line). For short field landing I use 70.

When you float over the runway it is very importand that lower the wing in to the wind.

[Pole Hill]

Jimmy The Big Greek: Thanks for that :ok:
What is the maximum crosswind limit for a single engine landing? I can't seem to find it..
Thanks,
POL

[Jimmy The Big Greek]

there is no single-engine crosswind limit as far as I know.

[Pole Hill]

Thats interesting, thanks for that. :ok:

[carbonfibre]

If i remember correctly from my limited experience on the BE-76 the limit was 25kt's(noticed on first post)

I agree with the other posts less flap and add 5kts to approach and VAT speeds

:ok:

[DFC]

Remember three things that can have an effect on situations such as these;

1. The reported wind is an average and will only include gusts if the gust reaches 10Kt or more above the average. Thus a wind with a general variation of 15 to 25 Kt with the occasional gustfrom 15 straight to to 29Kt will be reported as 20Kt.

2. The wind above the surface will usually be stronger.

3. In the northern hemisphere when the windspeed increases, the direction veers. Thus in this case a gust will cause a change in direction which will at least partially compensate for the increase in speed. Taking keygrips idea in a 90deg crosswind will result in gusts causing more crosswind and perhaps a bit of tailwind. Opposite when down under!

Thus if you kick it straight early, you could be trying to hold it straight in an actual 30Kt+ crosswind despite the reported surface crosswind being only 20Kt.

Regards,

DFC

[Tuned In]

Try without the rudder trim. I was always taught not to use it for the training - it is for cruising to nearest suitable and should be neutralised for the approach. Remember that in the real event the rudder required will reverse, due to the lower drag on the stopped or feathered engine than on the idling engine. Don't worsen this effect with trim!

[High Wing Drifter]

Tunedin,
Try without the rudder trim. I was always taught not to use it for the training - it is for cruising to nearest suitable and should be neutralised for the approach.
One of the admonishments dished out to me after my IR was that I took out all the rudder trim on final. It was strongly suggested that keeping some trim in will make my life easier to retain should an unexpected go-around be necessary.

[FlyingForFun]

Having read some replied suggesting use of partial or no flap, I started a related thread (http://www.pprune.org/forums/showthread.php?p=2806823) in the Tech Log forum to see what the experts there thought of the necessity to use less than full flap when the crosswind is lower than the demonstrated max.

Incidentally, the book speed for "over the numbers" on the approach is 76.

FFF
----------

[Pole Hill]

Tuned In & High Wing Drifter: I think from now on I will make the effort to remove most of the rudder trim - if I do this below ACH then there is no possibility of a GA. But do I want to be messing with rudder trim at 200ft, hmm, I think it shouldn't distract me...
FFF: I've just had a look at the thread, looks interesting. I've read some information on pprune a long time ago regarding reasons for using partial/no flap in crosswinds, and the general consensus was that the advantages outweighted the disadvantages. A few reasons were mentioned, and one, that hasn't been mentioned on this thread yet, is that the aircraft is more stable flapless in a crosswind.
Re over the numbers speed of 76, thats an interesting point. My FTO (and a few others that I know of) quote 80kts over the numbers in their operating data. Maybe this extra 5tks is causing the float that I have previously mentioned.
POL

[Tuned In]

As I said, I was told never to put any rudder trim in at all, as you never get to cruise single-engine. There should be no need for it on the go-around, as it is no worse than a fail on the climb but is expected, so should be easier to cope with.

[PAPI-74]

Forget the trim in the circuit, unless you are doing lots of them. Trim neutral on the Base leg after your PUFA check. You will have a low power setting and won't notice till the go-around.
Correct, the Vref (Vth) is 76kts....that explains your floating as the Duchess has a well designed wing.
If you have lost rudder authority, as stated, you are in the flare too long and as you get close to Vso / Vs and (if you are holding off too much) you will find it hard to get her straight.
Secret is nail the speed on the approach 85kts; nice smooth level off over the threshold 76kts till 72ish; straighten with rudder while you can and cross control feeding in more aileron as you get slower (and hold it on).
Should be a greaser.
Don't forget if the xwc if too much, you can take a 5kt tailwind in the Duchess and indeed most twins.

[Pole Hill]

Tuned In: Having thought about it, adjusting rudder trim below ACH, crap idea. Thinking about it, a few flights ago I did a few circuits without rudder trim to save me from adjusting it on finals, and I didn't find applying the required amount of 'leg force' continously a problem at all. I think that I've subsequently continued to put in trim because my instructor has recommended that I do so. I agree, theres no point using it unless in the cruise for the reason you mentioned in your second to last post. :ok:
PAPI-74: I won't be using trim in the circuit again, unless my leg begins to ache in which case I'll remove it on base! I'd like to try using 76kts at the threshold, but the FTO states 80kts. If I get chance though, I'll try using this speed to see the difference. :ok:
I think that the issues are that I shouldn't be using rudder trim in the circuit, and should use Vat=76kts, both contrary to my FTO's operating data. Well, if I ever fly the Duchess myself (i.e. at P1), I'll know what I really need to do! :)
POL

[FlyingForFun]

For what it's worth, I would always fly any aircraft in trim, both rudder and elevator, except for temporary trim changes.

That includes trimming the rudder in all stages of an asymmetric circuit, right up to the point where I consider that the extra workload of trimming on very short final is more than the extra workload of holding in a bit of rudder for a very short period before landing. The exact point at which this happens might vary from one circuit to another, depending on the rate of power reduction, but it's normally slightly before ACH.

I will agree that this is not set in stone, and that some pilots prefer not to trim for base and final. But I've never heard of flying the whole circuit out of trim before. And flying out of trim en-route "as you never get to cruise single-engine", what if you have an engine failure half way across an ocean? :ooh:

FFF
-------------

[PAPI-74]

Enjoy, that's the main thing. Trim is tended to be used in high workload situations, i.e. IFR (in my view that is).
The brain needs to be used to hold the rudder input if not trimmed and you therefore loose capacity for the approach and SOP's. When I did my MEP CPL/IR on the Duchess, it was an SOP to trim during the EFATO. If it was on an IRF departure, definately trim for your life. Circuit bashing...it's over in a few minutes; just throttle back ASAP and hang on.
If you don't put it to neutral as the gear and flap go down, the power changes can catch you out because you feet have become lazy.

Good luck!

[Fduarte]

I would guess, if you need more rudder control you get it with more speed, so less flaps... considering you have enough runway for a 5kt faster landing or so.
I've learned in theory of flight: Avoid full flap landing in high crosswind conditions, this way, maintaining control effectiveness..

[PAPI-74]

The only problem with flap is that it will increase downwash and take away some of your airflow. When you straighten up, the keel surface, the fin, will become turbulent, loosing rudder authority.
Less flap will give you better control for longer.
Too much flap in turbulence may be too stressful and the wing will stall at a lower angle of attack, which with gusts from underneath, is not good.
As was mentioned before...forget who, every approcach is different. Apply knowledge and feel what it is doing.

[scroggs]

Try without the rudder trim. I was always taught not to use it for the training - it is for cruising to nearest suitable and should be neutralised for the approach. Remember that in the real event the rudder required will reverse, due to the lower drag on the stopped or feathered engine than on the idling engine. Don't worsen this effect with trim!

As far as I know, I have no experience on this type or anything similar. However, it is standard multi-engine assymetric philosophy that rudder trim should be neutralised prior to the final approach (usually at or around 1000'). A major reason for this is that it's easy to trim in the opposite sense in the situation that Tuned In describes and this could be highly embarrassing on a go-around. Another reason is that rudder trim can compromise crosswind-landing performance.

For most aircraft, the Aircraft Manual, Pilot's Notes, FCOMs or similar should have recommended flying techniques for abnormal situations included within. Have a look what the manual says for your type. If a school teaches a generic technique for similar types, ask it what the reasons are for those particular techniques. If you are on a CPL course aimed at preparing students for the airline world, then techniques and SOPs should be aligned with airline practice where it is safe and logical to do so, and they don't counter the manufacturer's recommended techniques.

Scroggs

[Icarus Wings]

with regards not using rudder trim, what if your seat was to slide back meaning you couldnt reach the pedals? at least if you are trimmed the aircraft will keep flying where you want it to rather than spiralling out of control whilst you scrabble around trying to move the seat forward again.

[scroggs]

Is the seat sliding back inadvertently a major problem with this aircraft type? If so, should it really be airborne? Or perhaps just never flown off autopilot?

Scroggs

[Pole Hill]

Thanks for everybody's feedback, some interesting points have been made. :ok:

scroggs: I will question my FTO about the use of non-standard speeds, I haven't until now due to the fact that I am complying with their SOPs.

I'm on an asymmetric learning curve! I went flying earlier today, and did an asymmetric circuit with no rudder trim, and some assymmetric circuits with rudder trim - the trim was removed on the completion of the base turn to final. Despite what I've said, I've personally found that the latter method is prefered to the former. I found that using rudder trim in the circuit made it much easier to maintain heading.
I should be taking my test in a few weeks. :}
POL

[uppa2]

What about landing with one eng out, crosswind on live or dead eng? This question bothers me!