Hi everybody, it seems a silly question but I wonder why on the AFM of the Airplane it says that Flap 0º landings are prohibited...
I hear that while the authorities were certificating the DHC6 they forgot to approve the test with flaps 0º....is that true? Anybody knowns the reason ( and were to find the documented answer) for this limitation?
It's been a while but I don't remember Flap 0 landings being prohibited. If I recall correctly, we used to train for Flap 0 landings (Series 100/200/300). Only problem would be a possible tail strike - but that's what the tailskid is for.
Not sure if you are reading a genuine De Haviland AOM or a company altered one. Flaps and nose wheel steering are on one hydraulic system and brakes are on another, for obvious reasons. ie crappy day if you lost everything. On wheels, intermediate and tundra tyres, ski's and Whipline floats, flapless landings are an abnormal landing and just call for a higher calculated Vref based on the weight of the aircraft. Not really practiced, except in training. The de havilland wing is a remarkable thing and flapless landings are easily accomplished.
CAP (the canadian) floats on the other hand which are a very good performer in all conditions call for attitudes for landing similar to a hull ie (flying boat) and the "sweet spot" is a larger area with more flap and a slower speed than a less flap arrival. They are the most difficult config to learn, but very rewarding when you do so. But with a flapless landing on them, the ideal conditions are not rough nor glassy water but into wind, and both engines operating for maximum reverse. V ref is around 110 aposed to 70. And a sweet spot area of too nose low to too high of less than an inch of attitude. A challenge. And not practiced because of the risk of f#cking it up.
At one commuter airline, which had 38 twin Otters, one pilot there was nearly always performing takeoffs with zero flaps, due to his belief that the airplane would not fly on one engine otherwise.... and of course he dragged the tail on one, so was promptly shown the door. Now, I personally thought this guy was just a tad strange, as he left a job flying a JetStar to fly the deHavilland twin engine wonder. Go figure.
Flapless landings are prohibited as a normal operational practice. There are a variety of reasons for this, high touchdown speed and inability to successfully carry out a baulked landing in accordance with the certification criteria when operating in that configuration are two of them. de Havilland did not "forget to approve the test", that is utter nonsense. De Havilland did not approve 0° flap landings because they do not provide the margin of safety required by CAR 3 and SFAR 23, the two certification criteria that are applicable to the Series 300 Twin Otter.
Supplement 23 to the Twin Otter Supplementary Operating Data (PSM 1-63-1) provides some guidance to operators when a Twin Otter must be landed with flaps retracted. The title of the supplement includes the very clear notation EMERGENCY OPERATIONS ONLY.
Only flap 20° and flap 37.5° (full flap) landings are approved as normal operations practice for Series 300 landplanes. Flap 10° landings are approved during icing conditions, or if there is any risk of ice being present on any part of the airframe when landing.
V1...so your answer is yes? Regardless of emergency ops or not...I believe all certificated aircraft are required to be controllable at landing with no flaps...
My answer is that flapless landings are prohibited as a normal operational practice. There is information in the manual that provides guidance if an operator has to make a flapless landing due to emergency circumstances.
The aircraft can do it without problems, but, amongst other things, you cannot be assured of being able to successfully carry out a baulked landing from that configuration. That is one of the reasons why flapless landings are not permitted as a normal operations practice in Series 300 landplanes.
Great information, V1. It always amazes me to see how many top specialists you can get online in this forum. Thanks to PPRuNe, you really get the information you need. Thanks again.
Im flying in ADA (Aerolinea de Antioquia) here in Medellin, Colombia.
Actually we did a Flapless landing as training (because we did our training in the plane) just simulating a hydraulyc and brakes low pressure or a "ferry" flight, but as V1 said, it is prohibited as normal operation.
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and of course he dragged the tail on one, so was promptly shown the door.
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