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Re: CAF P-40N mishap? ...

Tue Mar 19, 2019 12:27 am

marine air wrote:Can the gear handle be pulled up and the gear retract on the ground like the P-38? Could there have been a mistake between the gear handle and the flaps or other handle? I don't know the P-40, just asking.


Yes, but what usually happens is the tail wheel retracts first & it results in a crunch to the bottom of the rudder.

Re: CAF P-40N mishap? ...

Tue Mar 19, 2019 8:13 am

marine air wrote:Can the gear handle be pulled up and the gear retract on the ground like the P-38? Could there have been a mistake between the gear handle and the flaps or other handle? I don't know the P-40, just asking.


The gear can be raised on the ground, however that is 100% not the case here. As mentioned above, tailwheel would collapse and so would the right MLG, unless it was loaded in such a way to keep it forward.

Re: CAF P-40N mishap? ...

Thu Mar 21, 2019 1:27 pm

Taylor Stevenson wrote:
marine air wrote:Can the gear handle be pulled up and the gear retract on the ground like the P-38? Could there have been a mistake between the gear handle and the flaps or other handle? I don't know the P-40, just asking.


The gear can be raised on the ground, however that is 100% not the case here. As mentioned above, tailwheel would collapse and so would the right MLG, unless it was loaded in such a way to keep it forward.


So what is the suspected cause of what happened?

Re: CAF P-40N mishap? ...

Fri Mar 22, 2019 8:09 am

OD/NG wrote:
Taylor Stevenson wrote:
marine air wrote:Can the gear handle be pulled up and the gear retract on the ground like the P-38? Could there have been a mistake between the gear handle and the flaps or other handle? I don't know the P-40, just asking.


The gear can be raised on the ground, however that is 100% not the case here. As mentioned above, tailwheel would collapse and so would the right MLG, unless it was loaded in such a way to keep it forward.


So what is the suspected cause of what happened?


Each retract cylinder on a P-40 has internal mechanical locks that lock each one in up/down position. It is possible for the locks in one cylinder to fail and cause that leg to collapse on the ground or fail to uplock if taking off. I am NOT saying that is what happened. Having seen this once before, just trying to add a little clarity.

Re: CAF P-40N mishap? ...

Fri Mar 22, 2019 11:24 am

CraigQ wrote:Each retract cylinder on a P-40 has internal mechanical locks that lock each one in up/down position. It is possible for the locks in one cylinder to fail and cause that leg to collapse on the ground or fail to uplock if taking off. I am NOT saying that is what happened. Having seen this once before, just trying to add a little clarity.

Thanks for the info.

Re: CAF P-40N mishap? ...

Fri Mar 22, 2019 12:16 pm

CraigQ wrote:Each retract cylinder on a P-40 has internal mechanical locks that lock each one in up/down position. It is possible for the locks in one cylinder to fail and cause that leg to collapse on the ground or fail to uplock if taking off. I am NOT saying that is what happened. Having seen this once before, just trying to add a little clarity.


It's nearly impossible for the P-40 gear locks to fail once locked in. Structure would rip out, or the gear activating links would buckle before the lock's would physically sheer off. While the gear can fail to lock up or down for a few reasons, the pilot should have adequate warning through the gear warning system. P-40 gear is pretty stout. Even lacking hydraulic pressure the main gear will stay locked once down.

Brandon

Re: CAF P-40N mishap? ...

Fri Mar 22, 2019 12:51 pm

I don’t know what happened in the incident.

It’s very easy to make a mistake with the P-40 gear. You have to trap hydraulic pressure in the cylinder. If the pressure bleeds off the internal locks disengage. So after extension, and double check with the hand lever, you must move the selector to Off.

Really Big Gotcha.

And after landing, it’s easy to grab the wrong selector and retract Gear instead of Flaps. They are side by side.

Not a good system, but it was all New in 1935 for the P-36.

Re: CAF P-40N mishap? ...

Fri Mar 22, 2019 1:00 pm

Dave Hadfield wrote:I don’t know what happened in the incident.

It’s very easy to make a mistake with the P-40 gear. You have to trap hydraulic pressure in the cylinder. If the pressure bleeds off the internal locks disengage. So after extension, and double check with the hand lever, you must move the selector to Off.

Really Big Gotcha.

And after landing, it’s easy to grab the wrong selector and retract Gear instead of Flaps. They are side by side.

Not a good system, but it was all New in 1935 for the P-36.


Dave, the P-40 gear is designed to stay locked even if you lose hydraulic pressure. I do agree though that if not flying with a clear head you could grab the wrong lever when going for the flaps.

Brandon
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