Landing with wing tips full DHC-6 ??

chubbee · Post by **chubbee** » Fri Sep 02, 2005 1:07 pm

I thought I remembered that you could not land on floats or rough strips with wing tip fuel in the Twin Otter, but I didn't see this restriction in the Flight manual when last I checked. Has this changed at some point??

just curious · Post by **just curious** » Fri Sep 02, 2005 2:43 pm

Landing a DHC-6 on a rough strip with full tips is a bad idea from the standpoint of the rear spar attach points. Half tips is max, and if it is a spot that requires tundra tires, I wouldn't take any.

Driving Rain · Post by **Driving Rain** » Fri Sep 02, 2005 4:24 pm

just curious wrote:Landing a DHC-6 on a rough strip with full tips is a bad idea from the standpoint of the rear spar attach points. Half tips is max, and if it is a spot that requires tundra tires, I wouldn't take any.

Thats good advice JC but it's interesting that in order to water bomb the tip tanks on our 300's must be full. Optimum dropping speed is at or just above Vb. Apparently full tips reduce the bending moments of the rapid weight reduction while bombing and the tip fuel is used return to base. Strange no?

Juggs · Post by **Juggs** » Fri Sep 02, 2005 6:05 pm

Driving Rain wrote:Apparently full tips reduce the bending moments of the rapid weight reduction while bombing and the tip fuel is used return to base. Strange no?

It does seem kind of strange. Although as far as bending moments go, landing on rough strips and water bombing the moments go in two completely different directions. Maybe the spars are stressed to different strengths in terms of bending moments?

chubbee wrote:I thought I remembered that you could not land on floats or rough strips with wing tip fuel in the Twin Otter, but I didn't see this restriction in the Flight manual when last I checked. Has this changed at some point??

I think it is in the supplements section not in normal operating procedures. I'm not near my manual so I'm not 100% sure.

just curious · Post by **just curious** » Sat Sep 03, 2005 10:50 am

It is in the tip tank supplement. It has to do with the force on the rear spar on deceleration, rather than the wingloading on water pick-up of tankers.

Driving Rain · Post by **Driving Rain** » Sat Sep 03, 2005 4:32 pm

just curious wrote:It is in the tip tank supplement. It has to do with the force on the rear spar on deceleration, rather than the wingloading on water pick-up of tankers.

We used to run the twotters with an array of stain gauges and the info gathered suggest it's not the loading but rather the rapid unloading that puts the most detrimental loads on the attachment points in the form of negative Gs.
DR

switchflicker · Post by **switchflicker** » Sat Sep 03, 2005 7:21 pm

I've only flown the Twin Otter on wheels and we were told to get the tips down to one half before landing. Don't remember seeing this in the AFM though.

Will someone comment on landing the Beaver on floats with the tips full? I'v done this may times but was never sure if it was OK

Thanks

Driving Rain · Post by **Driving Rain** » Sat Sep 03, 2005 9:33 pm

I flew them many years ago but I recall it was the same thing with the Turbo Beavers as it was with the Twotters. Our Fleet had at that time EDO water bombing floats and the manual required us to bomb wth the tips full.
The full tips allow the turbo beaver go to a higher gross weight also. I can't remember if this applies to the piston beaver.

Jeremy · Post by **Jeremy** » Tue Sep 06, 2005 9:22 am

For short nose Beavers with the upgross kit to 5300 lbs, the tip tanks need to be full as well.

RJ

chubbee · Post by **chubbee** » Thu Sep 08, 2005 11:42 am

Thanks much for the info.

dash2/3 · Post by **dash2/3** » Thu Sep 08, 2005 6:16 pm

the upgross kit on the steam beaver is actually to 5370lbs. and anything over 5090lbs must be in the tips.

also in the steam beaver, if the a/c has the modification (ie ag or military wing hard-points) the rivets in the underside of the wing have a different pitch allowing you to land with your tips full.

twotter · Post by **twotter** » Thu Sep 08, 2005 8:33 pm

Baron also has a kit for the Beaver that will allow you to go to 5370 without tips.. Plus there are others out there that will allow above that all the way up to 6000#..

dash2/3 · Post by **dash2/3** » Fri Sep 09, 2005 4:47 am

the 6000lb upgross is nice but very expensive and you'd be climbing a ladder to put fuel in the wings "a la cessna" which bye the way sucks ass in the bush