Lastordu From United States of America, joined Aug 2005, 367 posts, RR: 0 Posted (10 years 1 month 4 days 14 hours ago) and read 13473 times:
I know this a stupid topic. But just moved to RDU and it rains here a lot. So I was wandering do pilots use the windshield wiper just when taxing or do they use them on landing and takeoff. It is hard to see from the spot that I go to at the airport.
"Remember, Remember the 5th of November" from V for Vendetta
SlamClick From United States of America, joined Nov 2003, 10062 posts, RR: 66
Reply 5, posted (10 years 1 month 4 days 12 hours ago) and read 13360 times:
Quoting Lastordu (Thread starter): So I was wandering do pilots use the windshield wiper just when taxing or do they use them on landing and takeoff.
Didn't see this part.
Most wiper controls will have a speed control that should work like the interval wiper setting in your car. Thing is, though, that for some reason airplane wipers are really loud and kind of annoying. Older Boeing wipers are really annoying.
Also, your speed affects the apparent intensity of the rain. Going faster, even light rain will seem heavy because you gather so many more drops per second than you would standing still. So at slow speeds, like taxiing, the PNT (pilot not taxiing) will often turn them on and off from time to time.
Short answer - as needed.
The first real six-axis flight simulator I ever flew surprised me in this area. When "rain" was part of the airport weather conditions selected for its computer it blurred the picture outside unless you turned on the wipers. Then it synthesized the noise quite accurately. Made me laugh!
Happiness is not seeing another trite Ste. Maarten photo all week long.
Tornado82 From , joined Dec 1969, posts, RR:
Reply 6, posted (10 years 1 month 4 days 11 hours ago) and read 13310 times:
Quoting SlamClick (Reply 5): So at slow speeds, like taxiing, the PNT (pilot not taxiing) will often turn them on and off from time to time.
I saw this on a Commutair B1900 @ FWA on a rainy Sunday Aug 14th... I found it kind of funny that my 1999 ZX2 had delay/pulse/intermittent (whatever you want to call them) wipers and a multi-million dollar aircraft the pilot had to flip the switch himself.
Bellerophon From United Kingdom, joined May 2002, 586 posts, RR: 58
Reply 16, posted (10 years 1 month 2 days 23 hours ago) and read 12942 times:
FredT came the closest!
When the windscreen wipers were turned off after use, if they did not stow themselves in exactly the correct parked position, then they became an obstruction in the path of the visor as it was raised. In this situation, a microswitch would prevent any movement of the visor.
A close look at the second picture will show how tight the clearance was.
If the wipers didn't park correctly, the visor could not be raised.
If the visor could not be raised, then the nose could not be raised.
If the nose could not be raised, then supersonic flight was not allowed.
If supersonic flight was not allowed, then there was insufficient fuel onboard for a subsonic Atlantic crossing, so fuel jettison and re-land!
All in all, it was preferable and easier to put up with some rain on the windscreens, rather than risk a stuck visor and an unscheduled return.
Of course, taking-off in July from HAWK21M's home base would have been a different matter!
Euclid From South Africa, joined Apr 2005, 373 posts, RR: 0
Reply 17, posted (10 years 1 month 2 days 22 hours ago) and read 12920 times:
Quoting Bellerophon (Reply 16): When the windscreen wipers were turned off after use, if they did not stow themselves in exactly the correct parked position, then they became an obstruction in the path of the visor as it was raised.
Thanks for the answer, sir! After my stupid guess I've been wondering about it the whole night.
Undehoulli From , joined Dec 1969, posts, RR:
Reply 18, posted (10 years 1 month 2 days 20 hours ago) and read 12887 times:
One of our instructors here used to be a Saab 340 Captain before he went to Northwest - got furloughed, and is now back at UND. Anyhow, he told us about a time in the Saab (not his Saab) when the windshield wiper was turned on above its design speed....It departed the window, hit the left engine and caused it to fail, and when the wiper blade penetrated the fuselage and went into a passenger's leg. Three problems now...decompression, passenger with windshield wiper in leg, and engine failure. Where do you find this one in the QRH!!???
EMBQA From United States of America, joined Oct 2003, 9364 posts, RR: 10
Reply 20, posted (10 years 1 month 2 days 13 hours ago) and read 12804 times:
Quoting Undehoulli (Reply 18): One of our instructors here used to be a Saab 340 Captain before he went to Northwest - got furloughed, and is now back at UND. Anyhow, he told us about a time in the Saab (not his Saab) when the windshield wiper was turned on above its design speed....It Departed the window, hit the left engine and caused it to fail, and when the wiper blade penetrated the fuselage and went into a passenger's leg. Three problems now...decompression, Passenger with windshield wiper in leg, and engine failure.
Actually that is not 'fully' what happened. The aircraft, flying at night flew through a flock of Snow Geese. One of the Geese hit the nose area of the plane and took out the Capt's side windshield wiper. The airflow pushed the wiper into the LH Prop, which in turn slung it into the fuselage. It punctured the fuselage and struck the passenger in the leg seated in the second seat. He was injured in the leg and required a medical attention. The engine did not fail due to the wiper, but the prop was damaged. The engine was damaged by a second Snow Goose it ingested..!! The aircraft also required extensive repairs to several leading edges due to bird strikes. I remember when I walked on the not long after it happened it stunk and was a real mess. The hole was small enough that the plane did not depressurize. Some where in my files I have all the pictures..!1 What a mess.
[Edited 2005-09-09 22:48:07]
"It's not the size of the dog in the fight, but the size of the fight in the dog"
There is a speed restriction of 205 knots indicated so the wipers can be used on takeoff, approach and landing. The wiper system has 2 speeds, high speed which operates the wipers at 275 strokes per minute and the low speed at about half the strokes. The system consists of 2 motors above the pilot’s heads, one for each wiper. A flexible shaft from the motor is connected to a converter that converts the rotary action of the motor to the back and forth oscillating action of the wipers. Each wiper system is separate from the other but jointly controlled by one switch.
The wiper system is controlled by a switch on the overhead panel above the pilot’s head. The switch has 4 positions, park, off, high and low. When the wipers are stopped, they will stop wherever the power is cut off. To place the wipers in the park position, the switch is turned to park and the wipers will go to the most inboard position on the windshieldas shown in this photo.
The windshield wiper system is very noisy and distracting, especially during approach when total concentration is required so we never used them in flight. Once on the ground we would use the low speed if the rain was heavy and affecting our vision.
One time during cruise at altitude, the pilot’s wiper came slightly off the part position. The chief pilot was flying the airplane at the time so he reached up and turned the wiper switch to park to repark the wiper. Our airspeed was above the windshield operating speed so when the motor tried to park the wiper, the gear in the converter stripped and allowed the wiper arm to extend to the opposite side of the windshield. The air noise from the wiper was loud enough that we could not talk to each other unless we shouted. When we landed, I took the pilot's wiper arm off the external shaft, which was held on by one nut and we continued the trip without the pilot’s windshield wiper arm. We were lucky that the wiper assembly or blade was not torn off of the airplane, because Lockheed had a bulletin about inspecting the wiper system for integrity because if they were torn off for any reason the blades could be ingested into one of the engines that would result in an engine failure.
The chief pilot, who was a first class idiot anyway learned a lesson which cost the company a lot of money for a new windshield wiper converter, keep your hands off the wiper switch during flight. As chief of maintenance I had to appoave all maintenance and parts bills before I handed them to the chief pilot, he never said anything when I presented him with the bill from Lockheed for the part, he just signed it ok for payment. But if it was one of the other pilots in the flight department he would have read us the riot act and threatened to take it out of our pay