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-   -   Crosswind Landings in the BE76 (https://www.pprune.org/professional-pilot-training-includes-ground-studies/240338-crosswind-landings-be76.html)

Pole Hill 28th Aug 2006 12:48

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 28th Aug 2006 13:03

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

Pole Hill 28th Aug 2006 17:13

Thats interesting, thanks for that. :ok:

carbonfibre 28th Aug 2006 21:06

X-Wind limit
 
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 29th Aug 2006 10:06

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 29th Aug 2006 10:23

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 29th Aug 2006 11:42

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 29th Aug 2006 16:15

Having read some replied suggesting use of partial or no flap, I started a related thread 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 29th Aug 2006 17:02

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 29th Aug 2006 17:15

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 29th Aug 2006 18:01

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 29th Aug 2006 18:53

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 29th Aug 2006 19:20

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 29th Aug 2006 19:26

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 29th Aug 2006 21:04

Interesting!
 
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 29th Aug 2006 21:54

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 30th Aug 2006 07:29


Originally Posted by Tuned In (Post 2806136)
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 30th Aug 2006 09:41

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 30th Aug 2006 17:08

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 30th Aug 2006 20:40

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


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