Ice

[Aerodynamisist]

I was once told by an old salt that covering your wings tail nose ect with engine oil (1 or 2 litters) would help prevent build up of ice. I'm a little skeptical myself but it stuck in my head after reading the hotham thread, could any of the old salts out there shed some light on the subject.

I do not advocate this as a substitute for de-ice we all know the regs on flight into known icing conditions.

[chief wiggum]

If this were the case, then don't you think that it would be common practice ?

Personally, I wouldn't try it. Never know how it will affect the dynamics of the wing etc.

[tinpis]

Old salts love bull****tin newbies.
:p

[Continental-520]

Well, do you get clear ice build up beneath your engine cowls ever?

They are usually covered in oil.

I wouldn't try it either though, cause the cleaning job at the end of the flight would probably take me longer than the flight itself, no matter how long I flew for.

Easier to just not go flying in icing, assuming it's known.


520.

[swh]

"Well, do you get clear ice build up beneath your engine cowls ever? "

When the engine is shut down, and its cool enough for ice to form.

Sir Charles KS had a run in or two with ice building up on engines.

:ok:

[Sunfish]

Did this same old salt tell you to put anti-freeze in your battery?:}

[Continental-520]

Then what about on S/E aircraft under the belly?

Is there ever ice build up there? If so, would there be more ice build up if the belly was actually clean from oil/grime?


520.

[Milt]

Ice Accretion

Most aviators know that serious clear ice accretion occurs when you fly through supercooled water droplets or into freezing rain.

Undisturbed water droplets in some clouds can remain as water down to about -4C. As your aircraft collides with these droplets they immediately adhere and freeze on leading edges. Stay at that level long enough and you will fall out of the sky as your wings and engine air intakes take on leading edge lumps..

Freezing rain is often worse and occurs when you fly in sub zero air in a cold front. Rain falling from the warmer air above freezes on your sub zero surfaces and can build up very rapidly with flow back from the leading edges as the rain drops freeze more gradually than do supercooled drops. Once again nasty consequences unless you change level in a hurry.

[gaunty]

Continental-520

you'll get ice on any part of the airframe clean or not in the right conditions.

I guess one way to prove it is to empty the TV dinners out of a part of the freezer :} and put an oil covered and a clean bit of ally in it and see for yourself.

What may not be well understood is that neither does the air temp have to be 0C or less.

Most manufacturers will define the danger point for ising and so do the regs as when the Temp is at or below 5C down to -15C and there is visible moisture. This is a little misleading as just because there is no visible moisture doesn't mean its not there.

Just watch the condesation clouds on top of the wings of a "heavy" in clear but humid air.

It's the localised lower pressure areas on the airframe other than the wing that are the culprit and where it can form, often unseen even in "clear" air under the right conditions. Think venturi effect.

Under or inside cowls would be a good culprit given the design of them is to encourage cooling air around the cylinders. I suspect air is a sufficiently good insulator to allow ice to form quite close to the cylinders if in fact not around them given low enough temps.

Easier to just not go flying in icing, assuming it's known. good thinking 99:ok:

[NAMPS]

Sounds like something the Myth Busters should try out.

Anyway, can someone buy me a can of sparks for the grinder? :}

[Metro man]

Dont mess around with icing, if your aircraft isn't properly equipped and certified stay away. I fly a pressurised twin turbine with full deice gear and a couple of times have been forced to descend due ice build up. Remember the Convair crash in NZ ? That was put down to icing.

When you are iced up you are no longer flying the same aircraft that was certified. Handling characteristics, speeds etc all go out the window. You are now a test pilot in a very dicey situation.

[piontyendforward]

Dont forget about the other ICE events in NZ

Cessna Caravan off Kaikoura
B58 Baron at Levin
Convair off Paraparaumu

Getting ice: Get out!

[gaunty]

Metro man

Beautifully put. :ok:

When you are iced up you are no longer flying the same aircraft that was certified. Handling characteristics, speeds etc all go out the window. You are now a test pilot in a very dicey situation.

FWIW.

PART 23—AIRWORTHINESS STANDARDS: NORMAL, UTILITY, ACROBATIC, AND COMMUTER CATEGORY AIRPLANES
Subpart F—Equipment
Safety Equipment


§ 23.1419 Ice protection.
If certification with ice protection provisions is desired, compliance with the requirements of this section and other applicable sections of this part must be shown:

(a) An analysis must be performed to establish, on the basis of the airplane\'s operational needs, the adequacy of the ice protection system for the various components of the airplane. In addition, tests of the ice protection system must be conducted to demonstrate that the airplane is capable of operating safely in continuous maximum and intermittent maximum icing conditions, as described in appendix C of part 25 of this chapter. As used in this section, “Capable of operating safely,” means that airplane performance, controllability, maneuverability, and stability must not be less than that required in part 23, subpart B.

(b) Except as provided by paragraph (c) of this section, in addition to the analysis and physical evaluation prescribed in paragraph (a) of this section, the effectiveness of the ice protection system and its components must be shown by flight tests of the airplane or its components in measured natural atmospheric icing conditions and by one or more of the following tests, as found necessary to determine the adequacy of the ice protection system—

(1) Laboratory dry air or simulated icing tests, or a combination of both, of the components or models of the components.

(2) Flight dry air tests of the ice protection system as a whole, or its individual components.

(3) Flight test of the airplane or its components in measured simulated icing conditions.

(c) If certification with ice protection has been accomplished on prior type certificated airplanes whose designs include components that are thermodynamically and aerodynamically equivalent to those used on a new airplane design, certification of these equivalent components may be accomplished by reference to previously accomplished tests, required in §23.1419 (a) and (b), provided that the applicant accounts for any differences in installation of these components.

(d) A means must be identified or provided for determining the formation of ice on the critical parts of the airplane. Adequate lighting must be provided for the use of this means during night operation. Also, when monitoring of the external surfaces of the airplane by the flight crew is required for operation of the ice protection equipment, external lighting must be provided that is adequate to enable the monitoring to be done at night. Any illumination that is used must be of a type that will not cause glare or reflection that would handicap crewmembers in the performance of their duties. The Airplane Flight Manual or other approved manual material must describe the means of determining ice formation and must contain information for the safe operation of the airplane in icing conditions.

[Doc. No. 26344, 58 FR 18977, Apr. 9, 1993]

and here is part of Appendix C of Part 25.

PART 25—AIRWORTHINESS STANDARDS: TRANSPORT CATEGORY AIRPLANES
Subpart G—Operating Limitations and Information

Appendix C to Part 25
(a) Continuous maximum icing. The maximum continuous intensity of atmospheric icing conditions (continuous maximum icing) is defined by the variables of the cloud liquid water content, the mean effective diameter of the cloud droplets, the ambient air temperature, and the interrelationship of these three variables as shown in figure 1 of this appendix. The limiting icing envelope in terms of altitude and temperature is given in figure 2 of this appendix. The inter-relationship of cloud liquid water content with drop diameter and altitude is determined from figures 1 and 2. The cloud liquid water content for continuous maximum icing conditions of a horizontal extent, other than 17.4 nautical miles, is determined by the value of liquid water content of figure 1, multiplied by the appropriate factor from figure 3 of this appendix.

(b) Intermittent maximum icing. The intermittent maximum intensity of atmospheric icing conditions (intermittent maximum icing) is defined by the variables of the cloud liquid water content, the mean effective diameter of the cloud droplets, the ambient air temperature, and the interrelationship of these three variables as shown in figure 4 of this appendix. The limiting icing envelope in terms of altitude and temperature is given in figure 5 of this appendix. The inter-relationship of cloud liquid water content with drop diameter and altitude is determined from figures 4 and 5. The cloud liquid water content for intermittent maximum icing conditions of a horizontal extent, other than 2.6 nautical miles, is determined by the value of cloud liquid water content of figure 4 multiplied by the appropriate factor in figure 6 of this appendix.

I\'ll need to dig around to find out the MET forecasting equivalents, but if they FCST whatever then it prolly is.

[Meeb]

Back in the 50's an anti ice 'paste' was applied to leading edges of some aircraft of that era, with various results... :(

Maybe thats where this old salt got his idea of using engine oil from, but it would not have sufficient viscosity.

[HKG Phooey]

I used to fly the ATP and we put de-icing goo on the elevator hinges... But the elevator kept jamming... even after flying in clear air!!!


It seems that the cacin crew would pour the left over tea and coffee down the crack in the rear doors ( the toilet being at the front and they didnt want to walk all that way (18 rows)) and it would then ice up the elevator paste or no paste....

Made for some interesting impacts on the runway...

:\

[tinpis]

Continental 520
Well, do you get clear ice build up beneath your engine cowls ever?

I never got out and looked.

:p

[Continental-520]

But the day we get airframe icing up this end will be the day that I can walk into Qantas and say "Give me my 747 command job please...and, no layovers with that either thanks!"

Hahaha..... :D

520.

[Ski Guru]

I can't believe I read that. This place is still good for a laugh now and then.

Powder to the People

[ITCZ]

Sounds like bullsh!t to me. I wouldn't put any trust in oil or grease or suchlike.

One of the reasons you are advised to run an engine every now and then on an aeroplane that doesn't get much work, is that the oil is hygroscopic and has absorbed moisture. Running an engine heats the oil among other things and drives off some of the moisture.

As for greases, well I have had a few occasions when the Metro 23 horizontal stab 'stuck' in the cruise when moisture in the grease on the tail jackscrews, also hygroscopic, froze. Move the stab trim, no 'beep beep' and no trim change.

Don't believe everything you hear. Especially don't believe advice that might have you considering flying your aeroplane somewhere it wasn't certified to go.