deploying de-icing boots

[list2002]

I have been teaching the new idea that de-icing boots should be deployed as soon as visible ice is detected. Rather than 1/4 to 1/2 inch build up then deploy the boots. One student has asked me where I read that and we have not been able to find it.
Anyone know which AD or FAR this would be under?
Thanks

 

[80/20]

The technique to wait for some ice build-up before deicing wings are common in jets that use hot bleed air from the engines. Many pilots like to allow some ice accumulation to build up before turning wing heat on. This will provide the cleanest airfoil surface with the least possible "runback". "Runback" can cause new ice formation on unprotected places. As far as boots is concerned I have experienced conditions where premature use of the boots made a "bridge" of ice which prevented the boots from working properly (King Air & light piston twins) - but this might only be a problem on older airplanes as FlyChicaga is suggesting.

 

[xjcaptain]

Actually the guidance NOT to wait until ice has built up to a specified depth IS addressed by an AD. Here's a little more background on the Boot De-Ice info. This is specifically for the Saab 340, but the last part of the text pertains to other aircraft that were effected by the initial NPRM. You can do a search on the FAA site to find out about the particular outcome for each of the aircraft listed. I've also attached some of the background info prompting the issuance of these AD's. Hope it helps.



99-19-14 SAAB AIRCRAFT AB: Amendment 39-11303. Docket 99-NM-148-AD. Issued November 10, 1999.
Applicability: SAAB SF340A, SAAB 340B, and SAAB 2000 series airplanes equipped with pneumatic deicing boots, certificated in any category.

Compliance: Required as indicated, unless accomplished previously.

To ensure that flightcrews activate the wing and tail pneumatic deicing boots at the first signs of ice accumulation on the airplane, accomplish the following:

(a) Within 10 days after the effective date of this AD: Revise the Limitations Section of the FAA-approved Airplane Flight Manual (AFM) to include the following requirements for activation of the ice protection systems. This may be accomplished by inserting a copy of this AD in the AFM.

"o Except if the AFM otherwise specifies that deicing boots should not be used for certain phases of flight (e.g., take-off, final approach, and landing), compliance with the following is required.

o Wing and Tail Leading Edge Pneumatic Deicing Boot System, if installed, must be activated:
- At the first sign of ice formation anywhere on the aircraft, or upon annunciation from an ice detector system, whichever occurs first; and

- The system must either be continued to be operated in the automatic cycling mode, if available; or the system must be manually cycled as needed to minimize the ice accretions on the airframe.
o The wing and tail leading edge pneumatic deicing boot system may be deactivated only after completion of an entire deicing cycle after leaving icing conditions."

(b) An alternative method of compliance or adjustment of the compliance time that provides an acceptable level of safety may be used if approved by the Manager, International Branch, ANM-116, FAA, Transport Airplane Directorate. The request shall be forwarded through an appropriate FAA Operations Inspector, who may add comments and then send it to the Manager, International Branch, ANM-116 ACO.

NOTE 1: Information concerning the existence of approved alternative methods of compliance with this AD, if any, may be obtained from the International Branch, ANM-116 ACO.

(c) Special flight permits may be issued in accordance with sections 21.197 and 21.199 of the Federal Aviation Regulations (14 CFR 21.197 and 21.199) to operate the airplane to a location where the requirements of this AD can be accomplished.

(d) This amendment becomes effective on December 27, 1999.



SUPPLEMENTARY INFORMATION: A proposal to amend part 39 of the Federal Aviation Regulations (14 CFR part 39) to include an airworthiness directive (AD) that is applicable to certain Saab SAAB SF340A, SAAB 340B, and SAAB 2000 series airplanes was published in the Federal Register on July 16, 1999 (64 FR 38365). That action proposed to require revising the Airplane Flight Manual (AFM) to include requirements for activation of the airframe pneumatic deicing boots.

Related Proposals
In addition to the proposed rule described previously, in June 1999, the FAA issued 18 other similar proposals that address the subject unsafe condition on various airplane models (see below for a listing of all 19 proposed rules). These 18 proposals also were published in the Federal Register on July 16, 1999. (Docket 99-NM-153-AD, for Fokker Model F27 Mark 100, 200, 300, 400, 500, 600, and 700 series airplanes, was also issued as a supplemental notice of proposed rulemaking, and published in the Federal Register on August 6, 1999.) This final rule contains the FAA's responses to all relevant public comments received for each of these proposed rules.

Manufacturer Airplane Model Federal Register Number Citation
Cessna Aircraft Company Models 500, 550, and 560 Series Airplanes 99-NM-136-AD 64 FR 38374
Sabreliner Corporation Models 40, 60, 70, and 80 Series Airplanes 99-NM-137-AD 64 FR 38358
Gulfstream Aerospace Model G-159 Series Airplanes 99-NM-138-AD 64 FR 38341
McDonnell Douglas Models DC-3 and DC-4 Series Airplanes 99-NM-139-AD 64 FR 38325
Mitsubishi Heavy Industries Model YS-11 and YS-11A Series Airplanes 99-NM-140-AD 64 FR 38371
Gulfstream American (Frakes Aviation) Model G-73 (Mallard) and G-73T Series Airplanes 99-NM-141-AD 64 FR 38355
Lockheed, Models L-14 and L-18 Series Airplanes 99-NM-142-AD 64 FR 38338
Fairchild Models F-27 and FH-227 Series Airplanes 99-NM-143-AD 64 FR 38322
Aerospatiale Models ATR-42/ATR-72 Series 99-NM-144-AD 64 FR 38368
Jetstream Model BAe ATP Airplanes 99-NM-145-AD 64 FR 38351
Jetstream Model 4101 Airplanes 99-NM-146-AD 64 FR 38335
British Aerospace Model HS 748 Series Airplanes 99-NM-147-AD 64 FR 38319
Saab Model SF340A/SAAB 340B/SAAB 2000 Series Airplanes 99-NM-148-AD 64 FR 38365
CASA Model C-212/CN-235 Series Airplanes 99-NM-149-AD 64 FR 38348
Dornier Model 328-100 Series Airplanes 99-NM-150-AD 64 FR 38332
Lockheed Model 1329-23 and 1329-25 (Lockheed Jetstar) Series Airplanes 99-NM-151-AD 64 FR 38316
de Havilland Model DHC-7/ DHC-8 Series Airplanes 99-NM-152-AD 64 FR 38362
Fokker Model F27 Mark 100/200/300/400/500/600/700/050 Series Airplanes 99-NM-153-AD 64 FR 42870
Short Brothers Model SD3-30/SD3-60/SD3-SHERPA Airplanes 99-NM-154-AD 64 FR 38329

AGENCY: Federal Aviation Administration, DOT
ACTION: Final rule
SUMMARY: This amendment adopts a new airworthiness directive (AD), applicable to certain Saab SAAB SF340A, SAAB 340B, and SAAB 2000 series airplanes, that requires revising the Airplane Flight Manual (AFM) to include requirements for activation of the airframe pneumatic deicing boots. This amendment is prompted by reports of inflight incidents and an accident that occurred in icing conditions where the airframe pneumatic deicing boots were not activated. The actions specified by this AD are intended to ensure that flightcrews activate the pneumatic wing and tail deicing boots at the first signs of ice accumulation. This action will prevent reduced controllability of the aircraft due to adverse aerodynamic effects of ice adhering to the airplane prior to the first deicing cycle.
DATES: Effective December 27, 1999.
ADDRESSES: Information pertaining to this rulemaking action may be examined at the Federal Aviation Administration (FAA), Transport Airplane Directorate, Rules Docket, 1601 Lind Avenue, SW., Renton, Washington.

FOR FURTHER INFORMATION CONTACT: Norman Martenson, Aerospace Engineer, Manager, International Branch, ANM-116, FAA, Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton, Washington 98055-4056; telephone (425) 227-2110; fax (425) 227-1149.


SUPPLEMENTARY INFORMATION: A proposal to amend part 39 of the Federal Aviation Regulations (14 CFR part 39) to include an airworthiness directive (AD) that is applicable to certain Saab SAAB SF340A, SAAB 340B, and SAAB 2000 series airplanes was published in the Federal Register on July 16, 1999 (64 FR 38365). That action proposed to require revising the Airplane Flight Manual (AFM) to include requirements for activation of the airframe pneumatic deicing boots.

 

[LR25]

I think the reason for activating boots as soon as you see accumulation is for tail icing.

The tail collects ice for the most part twice what the wings will.

During training at Piedmont they showed some NASA test footage of a Twin Otter for tail icing. It opened my eyes up real wide.

I believe it was Comair that had a Brasilia about 2 years ago lose control coming in from the Bahamas becuase of tail icing.

 

[80/20]

Good NPRM information xjcaptain.
I wonder if similar changes have been made to all boots systems?
What about aircraft not included in this NPRM?

My old King Air manuals from 1984 state:

"THE BOOTS OPERATE MOST EFFECTIVELY WHEN APPROXIMATELY ONE-HALF TO ONE INCH OF ICE HAS FORMED. VERY THIN ICE CRACKS AND MAY CLING TO THE BOOTS."

Have the King Air manuals been changed - anyone?

 

[supsup]

Try AOPA

I just read recently that the aopa publication on ice has been revised. It is supposed to address many of the comments on previous posts.

supsup

 

[cvsfly]

Our BE-B200 (1996) POH was revised with the AD and subsequent to that. Don't rely on outdated manuals. Also our FSDO recently has given us an Inspectors Handbook bulletin that requires us to incorporate minimum airspeeds for icing in our POH (if not already there) and our training program. I think the main theory behind activating the current generation of boots at first sign of ice is that the newer boots operate at higher pneumatic pressure and the "balloons" are smaller and closer together compared to older generation boots (DC-3 style, I assume). I still find that activating the boots on the KA after a 1/4 to 1/2 in breaks the ice more cleanly.

 

[Cargoboy]

I find that in the C310 when I am flying cargo and waiting til you get a good build up say more of a 3/4 to 1 inch cause of the style boots we have (old) pops the ice off better than if I pop them with say only a 1/4 inch. After trying both ways and then getting on the ground and observing the differences as to what is left, the more build up and then pop got them cleaner. Even the tail was better. But, there really is no perfect way to know what is the best time. Plus you are guesstamating the depth of build up. See what the POH recommends and the main thing is you don't want as much to let that tail stall out. That is the most important. Plus watch your gyros after you pop them. We get a good deflection and I have heard that some other pilots have lost a gyro. So, constant popping can create other problems as well. obviously the best philosophy is to get out of the icing but if you have to be in it, way out your possiblities and don't get carried away. Most planes can handle a good load of ice, it def. boils down to your ability and where it is at and your familiarity with the plane and how it handles in those conditions.
Keeping the plane under control can mean maybe landing and waiting for a better time to fly. I have had ice build up to the need of popping them in under one minute. On approach full power and you are just able to hold altitude. A lot going on and your attention has to be at its best. Anything goes wrong or you are behind the airplane and you can have a world of problems on your lap.
Happy flying........in the midwest.

 

[cvsfly]

The latest greatest from the FAA is AC 91-74. Any operating procedure published in the aircraft POH/AFM should be followed (which many in last few years adopted an AD 98-20-38 into the POHs). Air carriers will be getting a notice from their POIs # 8400.39 on this subject.

 

[JetPilot500]

The technique to wait for some ice build-up before deicing wings are common in jets that use hot bleed air from the engines. Many pilots like to allow some ice accumulation to build up before turning wing heat on. This will provide the cleanest airfoil surface with the least possible "runback". "Runback" can cause new ice formation on unprotected places.

If a JET uses bleed air heat on the wings, it is an "ANTI-ICE" system not a "DE-ICE" system.

The Anti-ice system is to be turned on before entering the icing condition. This is especially important in aircraft with aft-mounted engines. If you had an ice build-up on the wings and turned on the "anti-ice" you could ingest ice into the engine and FOD it out.

Sorry but I have never heard of your technique, and I think it may be dangerous in some aircraft. I see you fly the B737 (wing mounted engines), is this an ok or normal procedure in that aircraft?

JetPilot500

 

[puddlejumper]

Anti-Ice in Turboprops

Hey, I'd like to get everyone's opinions on turboprop anti-icing procedures. On a Cheyenne II, engine anti-ice is all on one switch. Turning it on heats the inlet boot, propeller blades and repositions the ice vanes and doors for the engines. I stay conservative and go by the book. Less than +5C and in visible moisture, everything goes on. I've been told that that isn't necessary until ice actually starts accumulating. The ice-door on the intake of a Cheyenne II is always open about an inch, although the deflecting vane is retracted. My concern is twofold. FODing the engines with the ice in the air or potential chunks off the lip I can't see and getting a buildup on the prop blades and banging up the avionics doors. During the day, accumulation is easy to see by looking back at the horizontal stab leading edge or keeping an eye on the windshield wipers.

What do y'all do? I'd like to hear what the SOP is with other TP operators. Thanks.

-PJ

 

[cvsfly]

In this aircraft, normally you will turn on engine anti-ice in any precipitation when the temperature is below +10 degree Celsius.

From the Southwest Airlines FOM:

"Warning: Do not rely on airframe visual icing cues to activate the engine anti-ice. Delaying the use of engine anti-ice until ice build up is visible from the cockpit may result in severe engine damage. Use the temperature and visible moisture criteria specified above."

Specified was +10 degrees Celsius and below, in visible moisture (clouds, fog with visibility less than 1 mile, rain, snow, sleet, ice crystals, mist).

So if ice is never adhering to the wings due to anti-ice, runback really shouldn't be a problem, most of the time.

That is for the B-737 series.

You are talking engine anti-ice here? That won't have much to do wing anti-ice or wing de-icing procedures. Engine anti-ice for the most part is protection against FOD. With minor accumulations and break-off of ice on an engine inlet lip I think there little concern of a flame out. But ice will abrade engine turbine blades. Not good for long life. On the PT-6 the ice vanes/inertial separators/engine-anti-ice are deployed anytime you are in visible moisture and < 5*C. Late model KA use engine inlet lip heat all the time as exhaust is routed through it.

 

[cvsfly]

Re: Anti-Ice in Turboprops

Hey, I'd like to get everyone's opinions on turboprop anti-icing procedures. ......
What do y'all do? I'd like to hear what the SOP is with other TP operators. Thanks.

-PJ

You are right. Everything to do with the powerplant - props, engine inlet, ice-doors - get them on early for everything you stated. With hot props if you wait to get it on you will definately put dents in the nose. What about alcohol props? Wing de-icing by virtue of the term requires some accumulation prior to boots being effective, just some aircraft POHs have adjusted the recommended amount of accumulation prior to inflation. Wing anti-ice (heated with bleed air) I would think it would be a "get it on early" deal, especially considering tail mounted engines, but I have no experience this. Then there is alcohol - weeping wings. I imagine that is classified as de-icing. On the Citations that have it, are the inboard sections of the wing (in front of the engines) equiped? What about the new technology of sonic/mechanical pulse de-icing systems?

 

[80/20]

JetPilot500 asks about 737 wing anti ice procedures and points out that different aircraft types may have various procedures. There is obviously not a single correct answer to our discussion.

Boeing gives this description in their current 737 manuals:
“Wing Anti–Ice Operation – Inflight
The wing anti–ice system may be used as a de–icer or anti–icer in flight only.
The primary method is to use it as a de–icer by allowing ice to accumulate before turning wing anti–ice on. This procedure provides the cleanest airfoil surface, the least possible runback ice formation, and the least thrust and fuel penalty.
The secondary method is to use wing anti–ice prior to ice accumulation. Operate the wing anti–ice system as an anti–icer only during extended operations in moderate or severe icing conditions, such as holding.”

In my experience the biggest 737 ice problem is engine fan icing; it's nasty and dangerous when it happens because it is difficult to remove and will quickly damage the engine. This phenomena is not caused by ice from the wings but other adverse weather conditions such as freezing fog.

 

[Deftone45075]

Hey, I'd like to get everyone's opinions on turboprop anti-icing procedures.

In the J31, any time there is visible moisture at an OAT of <10 C, the engine anti-ice, ignitors, and prop heat go on. The switch for the engine anti ice also turns on the Elevator horn anti ice pad to prevent the elevator from freezing in place.

As we have the older wing/tail boots, we wait until a little ice builds up before cycling them.

 

[El Bucho]

On the Mu2 there is an AD that in icing conditions you must hand-fly the aircraft and the boots placed in the auto mode. I think the auto mode blows the boots like once every 2 or 3 minutes. When to hit the switch will probabloy be debated until the cows come home. I've had the ice bridge the boots both ways whether I let it build up first or turn them on right away. The Mu2 has had extensive tests for icing. Flying behind the tanker and everything and I guess they found that even if the first cycle doesn't get it off, subsequent cycles will remove the ice most of the time.