Primarily for general aviation discussion, but other aviation topics are also welcome.
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By PeteSpencer
#1671586
foxmoth wrote:If you operate a retractable I am surprised this was not part of your training, once airborne you cycle the gear at least three times which should dislodge any slush picked up on take off.


Thanks: though the customary element of Forum snark was not necessary.

Peter
By Harry Brown
#1671587
Awful Charlie wrote:?..glycol... too much glycol will make it harder to spray. Glycol will absorb water...


Home brewed de-ice fluid is a money saver but too much glycol will inhibit the shear speed. You don't want to get airborne with glycol covered wings. .[/quote]

Inhibit Shear Speed? You do ideally want to get airborne with glycol or more correctly low foaming propylene glycol covered wings, that is the whole point of anti icing. On jet transport aircraft that require wing tactile tests during the walkround in icing conditions you can still feel the propylene glycol on the wing from the previous deicing. The whole idea is it adheres to the wing to give you holdver time (which is also dependent on precipitation and temperature)

No fluid should go near the fuselage where it could flow over a windscreen on take off or near an APU which should be switched off for anti icing/deicing . Fuselages do not need to be deiced although unbelievably one morning a new deicing crew deiced our fuselage instead of the wings!

One morning the ATR next to us was being deiced and I could see some sort of argument developing between the captain and the leading hand. Turns out the captain was a management pilot and told the crew that as he had not ordered deicing the company were not going to pay for it. They subsequently took off with only one wing deiced. I am pleased to say that airline is no longer operating.

In the 70s I remember the CFI of a Scottish Flying School brushing loads of snow off a Cessna 150s wing with a broom and then taking off for Dundee. He spun in just after take off but survived.
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By Paul_Sengupta
#1671589
PeteSpencer wrote:Thanks: though the customary element of Forum snark was not necessary.


Not snark. Two posts appeared between "there's a procedure" and "what is it?" meaning that it wasn't immediately obvious what question was being asked. Quoting might have helped in this instance.
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By PeteSpencer
#1671590
'I'm surprised this was not part of your training' could easily have been omitted from the answer: It added nothing to the advice.
Andy's 'leave the wheels down' sound much less of a faff.

I happened into the 'retractable sign off' era with long standing grandfather rights: In fact my instructor said:

'Here's the gear knob, up for up and down for down, and don't pull it off' - there had been a recent case in the USA where a pilot had pulled the knob off with the gear up, necessitating a bit of on the hoof creative thinking.

Peter :roll:
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By Paul_Sengupta
#1671592
PeteSpencer wrote:'Here's the gear knob, up for up and down for down, and don't pull it off' - there had been a recent case in the USA where a pilot had pulled the knob off with the gear up, necessitating a bit of on the hoof creative thinking.


I believe the "pulling the knob off" thing happened to Aerbabe and Aerbloke in a Seneca (?) which meant Aerbabe had to go scrambling around to find the knob in order to reattach it.
User avatar
By Lockhaven
#1671600
PeteSpencer wrote:
Lockhaven wrote:
ChrisRowland wrote:What is it?


What ?


Oh another bleedin’ comedian :roll:

Care to share the procedure you alluded to in response to my post with the rest of us ignorami ?

Peter


This the procedure for our aircraft it may help with yours, its the procedure on the larger aircraft I fly.

1. During taxi warm the brakes as much as possible up to a max of 150 C to remove slush, rain and moisture (ok we have brake temp gauges and carbon brakes) so be careful with steel brakes.

2. After take-off delay the retraction of the gear to blow any remaining water/ moisture away.

3. During the descent if our brake heat is not working, (insert you don't have brake heat fitted) we cycle the parking brakes 6 times to release any frozen deposits, I guess for your aircraft operate the brake pedals, so cycle those to maximum pressure.

Ps wasn't being a comedian just didn't understand who the question "What is it?" was directed at or who too.
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By PeteSpencer
#1671608
Paul_Sengupta wrote:
PeteSpencer wrote:'Here's the gear knob, up for up and down for down, and don't pull it off' - there had been a recent case in the USA where a pilot had pulled the knob off with the gear up, necessitating a bit of on the hoof creative thinking.


I believe the "pulling the knob off" thing happened to Aerbabe and Aerbloke in a Seneca (?) which meant Aerbabe had to go scrambling around to find the knob in order to reattach it.


In the US case, the knob actually snapped off, leaving nothing to see or grab onto.
ISTR pax nail file saved the day.

Peter
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By AndyR
#1671809
Pete, if it helps, I was never taught it either.

Which one doesn’t tend to find out until one would really like the gear doors to open on approach half an hour later, when operating in a cold snowy environment, with lots of icy spray from the runway. It’s naturally now part of our SOPs.

ILAFFT.
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By Lockhaven
#1671814
Harry Brown wrote:Fuselages do not need to be deiced although unbelievably one morning a new deicing crew deiced our fuselage instead of the wings!


That statement is not completely true some types do require the fuselage de-icing.
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By Flintstone
#1671843
Flintstone wrote:Home brewed de-ice fluid is a money saver but too much glycol will inhibit the shear speed. You don't want to get airborne with glycol covered wings. .


Harry Brown wrote:Inhibit Shear Speed? *You do ideally want to get airborne with glycol or more correctly low foaming propylene glycol covered wings, *that is the whole point of anti icing.


For a short time at the beginning of my career I too thought this (*) but it simply wasn't explained to me properly the first time around.

De-icing as it is commonly called is often but not always a two-step process, first the de-icing (removal) followed by anti-icing (prevention). The purpose of anti-ice fluid is to prevent re-contamination on the ground between de-icing and getting airborne. Once the aircraft has passed a given speed during the take-off roll it (the fluid) is no longer needed as the airflow prevents precipitation from adhering. In fact were the fluid to remain it would have an adverse effect on the wing's performance (for simplicity's sake this includes the tailplane).

Having fluid on the wing in flight is a bad idea in a similar way to having frost, ice and other contaminants there. It degrades laminar flow and raises stall speeds. Anti-ice fluid is therefore manufactured to a known viscosity so as to allow it to run off the wing somewhere between a 'safe' speed (where snow/ice/cold cack can't stick) and before rotation. From the NASA website:
Aerodynamic acceptance: to ensure the fluids do not compromise the aerodynamics of the aircraft at the point of take-off; ideally the fluids blow or shear off the wing & tail surfaces during the take-off roll.

https://aircrafticing.grc.nasa.gov/2_3_2_1.html

(Apologies for the bright red text but this is a dull subject that I thought could do with some livening up.)

The leading edges and cowls are of course still at risk but they are protected by the anti-ice systems, essentially a piccolo tube within the leading edges and cowl openings through which flows bleed air tapped from the engines. But I digress...

For the benefit of readers unfamiliar with the sticky stuff here's a quick and dirty low-down on the four main types:

Type I. Red/orange, minimal holdover time (HOT**). No min rotation speed (so safe for use on all aircraft types). This is typically used to de-ice an aircraft prior to applying anti-ice fluid.
Type II. Clear/straw, HOT varies (see below) but typically 00:20-00:45 minutes. Minimum rotation speed 100 knots.
Type III. Yellow/green. HOT 00:10-00:20 minutes. Minimum rotation speed 60-100 knots.
Type IV. Emerald green. 00:35-1:15. Minimum rotation speed 100 knots.

** HOT will vary considerably dependant upon OAT, mixture ratio (100:0, 75:25 or 50:50 with water), temperature of mixture, brand of glycol and type of precipitation. The FAA, NASA, Transport Canada and other authorities update the holdover data tables annually.

Harry Brown wrote:On jet transport aircraft that require wing tactile tests during the walkround in icing conditions you can still feel the propylene glycol on the wing from the previous deicing.


Thanks. I know the procedure quite well and at this time of the year conduct it several times a day. What you describe as remaining from previous de/anti-icing is simply a 'leftover' due to there not yet being a fluid that will run off completely by airflow alone. In fact it must be removed (usually by blasting with hot Type I) before treating the aircraft again for another flight.

Harry Brown wrote:No fluid should go near the fuselage where it could flow over a windscreen on take off or near an APU which should be switched off for anti icing/deicing .


Quite so. In fact I think someone looking a lot like me and wearing my clothes wrote something about that at the bottom of the first page of this thread. :wink:
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By Iceman
#1671885
Paul_Sengupta wrote:
PeteSpencer wrote:'Here's the gear knob, up for up and down for down, and don't pull it off' - there had been a recent case in the USA where a pilot had pulled the knob off with the gear up, necessitating a bit of on the hoof creative thinking.


I believe the "pulling the knob off" thing happened to Aerbabe and Aerbloke in a Seneca (?) which meant Aerbabe had to go scrambling around to find the knob in order to reattach it.



Yes, it was a Seneca 3, the one that myself, Aerbabe and Aerbloke took to the Faeroes for the eclipse. It wasn't the first time that it had happened on that aircraft either. The trouble is is that the action of the emergency lowering system necessitates that the main gear handle is in the down position which if the handle is in your hand and the gear is up, presents a bit of a problem. Both occasions were rescued by the use of a biro jammed in to the now vacant gear handle position to force the gear down.

Iceman 8)
Last edited by Iceman on Tue Feb 05, 2019 11:01 am, edited 3 times in total.
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By kanga
#1671898
where I worked in Northern Canada was a settlement on a rock-free level narrows of a fast flowing river between two lakes. The current meant that the water remained unfrozen long after the lake surfaces had frozen in autumn/winter. It sometimes happened that the pilot of an aircraft on amphibious floats, taking off on floats from warmer open water well to the South and intending to land on wheels on a nearby hard runway, forgot to cycle the gear several times after takeoff to clear the splashed water from the mechanism, particularly around the nose wheels' bays and legs as well as the larger main gear doors. By the time the aircraft reached our area with its significantly colder air the gear was frozen up. Sometimes the aircraft would alight on our little patch of open water. The slightly warmer water would allow the gear to be cycled (still in the water at our dock!), whereupon it would be retracted. the aircraft would take off on floats, and the pilot would immediately put the gear down for landing on the nearby runway.

An alternative was to land on floats on a patch of graded snow , kept graded level on a blown snowbank between runway and taxiway at the nearby airport for precisely this purpose.
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By alexbrett2
#1671956
Iceman wrote:The trouble is is that the action of the emergency lowering system necessitates that the main gear handle is in the down position


Interesting, I'd vaguely thought the Seneca gear system was similar to the Arrow - with that as long as you pull the circuit breaker for the hydraulic pump (so that it won't immediately try and pump the gear back up), you can do a manual extension with the gear switch in the up position...

Obviously you then have to be extremely careful not to push the breaker back in (e.g. if you have a bit of a bump on landing, though hopefully the squat switch should then prevent retraction anyway), but it should be possible...
By ChrisRowland
#1671958
Iceman wrote:Both occasions were rescued by the use of a biro jammed in to the now vacant gear handle position to force the gear down.

Iceman 8)

The Apollo 11 fix.
Apparently the top of one of the circuit breakers was knocked off in the cramped quarters of the landing module. The Ascent Motor Arm CB. Also fixed using a pen to set the CB. (There was a work round, fire the ascent motor manually.)
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