Thread: flaps
View Single Post
  #7  
Old July 10th 07, 01:51 PM posted to rec.aviation.owning,rec.aviation.piloting
Roy Smith
external usenet poster
 
Posts: 478
Default flaps

"Kobra" wrote:
On base at Williamsburg I noticed that the airspeed was really high. I
raised the nose and pulled some power. I had 20 degrees of flaps in and
that is what I usually land with. On final the airspeed was just coming out
of the green and touching the white arc with only 15 inches manifold
pressure. On short final I dropped the last 10 degrees, but despite that,
man I came across the threshold like a bat-out-of-hell.


Then you should have gone around. Plan every approach to be a go-around,
and only make the decision to land when you get to the threshold and
everything is good.

10 kts too fast over the threshold is pretty significant. I don't fly the
177RG, but I found a checklist on the net that lists normal landing speeds
at 60-70 kts and Vfe (top of the white arc, which is what you said you were
doing on final) as 95. That's 25-35 kts too fast to land. I'm amazed you
managed to get it stopped in 3000 feet. In fact, I can't believe you were
really going that fast over the threshold, it's just not possible.

The runway was only 3000 feet, but somehow I got it down and stopped after
heavy brake burning. I just figured I used some really bad technique or
picked up a tailwind.


A tailwind will increase your groundspeed, but not your airspeed.

Now I had to get home. I called my mechanic and he said it could be many
things (it wasn't the breaker). He also said I was a complete wimp (he used
a different word that began with a p) if I couldn't land that plane without
the flaps on our 3,500 feet of runway.


From a strictly legal point of view, if you knew the flaps were broken, the
plane was not airworthy. From a safety point of view, however, I'd say you
did the right thing by consulting a mechanic to get an experienced opinion.
Technically, you needed a ferry permit to take off again, and your mechanic
using the p-word on the phone doesn't quite qualify. But I digress.

I took off and started to ponder the situation:


The pondering should have happened before you took off. Once you're in the
air, you can ponder all you want, but you still need to land the airplane.

No flaps
No daylight with 3 miles vis. in haze and mist (ASOS said 10 miles but no
way could you see more than 3 miles)
No landing light (it burned out two weeks ago)
No wind (so no headwind to help slow the airplane's ground speed on landing)
and I've done a grand total of two no-flap landings in my life. One with my
primary CFI and one during my check out when I bought the plane. Both
during the day with a headwind.


From a pure performance point of view, your mechanic was right. With
proper technique, landing a 177RG on 3500 feet without flaps and zero wind
should be a no-brainer. Even on a hot a muggy summer day like it was this
weekend, there's plenty of performance margin to make it a non-event if you
know how to do it.

But, at night, in poor visibility, with no landing light to help you judge
your height above the runway, and having never practiced them seems like
the wrong time to be learning. None of these things are serious by
themselves, but it sounds like it all adds up to a case of get-home-itis to
me.

I used runway 19 because runway 1 has trees on the approach and I wanted to
come in as flat as possible.


That sounds like a good decision.

Anyway...how many different things can cause this? Where should I start
looking?


Piper and Cessna took interesting divergent paths when they designed their
airplanes. Piper decided they were going to use electric trim and manual
flaps. Cessna decided on electric flaps and manual trim. In both cases,
each manufacturer added one totally unnecessary electric system and thus
saddled their owners with forever pouring money into fixing them. Maybe
the high-wing design made it difficult to engineer a manual flap control
linkage? In any case, if it's not the breaker, if could be the actuator
switch, the motor, one of the micro-switches that limit movement, or any of
the wiring in between. Just bring it to your mechanic with your checkbook
and let him put another kid through college :-)

I also recommend that everyone do some no flap landings each year.


Indeed. If you fly something with electric flaps where flap failures are a
way of life, maybe a lot more often than that. With practice, no-flaps
landings in a 177 should be a piece of cake. Slips help, so practice those
too.