DE-ICE OR ANTI-ICE, A DECISION THAT CAN COST YOU YOUR LIFE

Aircraft wings and tails have forever been the collectors of enough ice to make them quit working like wings and tails. All it really takes is visible moisture, a cloud for example, and temperatures that approach freezing. The movement of the metal surfaces through the air is often enough to lower the temperature below freezing so even outside air temperatures above freezing will allow enough ice to form to give plenty of aerodynamic trouble.

Aircraft manufacturers have historically used de-ice devices to deal with ice, at least enough of it to satisfy the FAA’s paltry requirements to certify an aircraft for flight into “known icing conditions”. De-ice devices concede that the manufacturer will allow the aircraft to accumulate ice before activation is supposed to shed the ice, hence the term de-ice.

De-icing devices are typically rubber boots that inflate to break the ice off. The inflation pressures are supplied by an engine driven vacuum pump, bleed air taken from the compressor section of turbine engines or separate pumps electrically driven. Engine driven vacuum pumps have proven to be prone to failure just when they are needed most because of heat, sudden demands that fail their internal carbon blades, general deterioration or contamination just to name a few of the many reasons for un-annunciated sudden failure. Bleed air drawn from the compressors of little turbine engines is often not enough to completely inflate the boots, the air can often becomes contaminated with moisture and causes ice to form in the inflation tubes, and bleed air drawn from the compressor means less air for the engine to develop the necessary power to climb out of icing conditions or even to provide cabin heat.

Electrically driven air pumps is clearly the better idea because the pumps are single purpose and can supply full inflation pressures regardless of aircraft altitude, cabin heat requirements or moisture.

All of these systems share the same problem. They are designed to remove ice allowed to accumulate rather than preventing its accumulation. It is the accumulation of ice that has proven to be the undoing of many pilots and their aircraft because the manufacturers have hidden a very important fact. They don’t work effectively in the icing conditions that these airplanes regularly fly in and that most pilots think are safe to fly in. None of the federal agencies have taken strong action but there has been talk for decades about the problem. Nonetheless people continue to die each icing season.

Most deicing boots cover less of the airfoil than is required to remove dangerous accumulations of ice. Most deicing boots are impacted by the lack of adequate inflation pressure especially at altitude or with cabin heat on, and many deicing boots will accumulate moisture that will affect the amount of inflation. Couple this with some very unforgiving airfoils that have sharp stall characteristics and the use of deicing boots for known icing certification can be disastrous.

Federal authorities have been uniform in blaming pilots for icing accidents. Clearly these blame merchants are either not pilots, or have never flown in the clouds in the winter. Icing is unpredictable and even when forecast occurs only forty percent of the time. To blame a pilot for a crash because he didn’t predict weather even the National Weather Service can’t get right seems unfair since for the most part pilots are unaware of the limitations of their deicing equipment as manufacturers have not been honest about the limitations.

OTHER THAN TRACE TO LIGHT ICING, DEICING EQUIPMENT IN MOST GENERAL AVIATION AIRPLANES DOESN’T WORK.

Neither the testing nor the equipment was ever designed to permit continuous flight in moderate icing conditions. The regulations require it but the manufacturers do not test for it and the aircraft will not handle it. Not a believer, look at the accident reports. They are replete with pilots who cannot believe their multimillion dollar aircraft can’t handle continuous moderate icing, a question they no doubt carry to their deaths.

Even the manufacturers can’t agree with either each other or the Government about when to de-ice. Some say wait until three quarters to one inch of rime ice accumulates before activating the boots. Others say, no, activate boots at the first sign of ice. Some say wait for less clear ice to accumulate before activation and others say activate the boots when such ice is anticipated. Some say don’t activate the boots on approach because it will slow the aircraft by ten knots or so and other say use the boots continuously. Some say ice bridging occurs if you use the boots too soon and too frequently and others say that’s an old pilot’s tale, dead old pilot no doubt.

Some NACA five digit airfoils, widely used in general aviation and some smaller turboprop commuter aircraft grow ice aft of the boots just because of their angle of attack in flight. Some will accumulate ice aft of the boots at the highest point of lift at twelve percent cord and others will react violently especially when the ice accumulates on the horizontal tail. Some airplanes will suffer an ice-induced tail stall for which recovery virtually no pilots have been trained. It is opposite normal stall recovery and may not be recoverable at all.

The manufacturers of big airplanes, transport category airplanes, have long recognized that the use of deicing boots is not a safe solution for the demands of air carriers who may have to fly in ice for a long time. Years ago they abandoned de-icing boots in favor of anti-ice systems. As one famous aeronautical engineer from a well known manufacturer has said: “You could not expect de-icing boots to effectively remove ice from an aircraft that had to fly from Paris to New York much of it in icing conditions so we heated the leading edges of the surfaces instead so ice wouldn’t accumulate.”

Anti-ice as it is called is the only safe way to keep modern aircraft safe in icing conditions. Heating the leading edges of the aerodynamic surfaces is the best way. In turbine aircraft, bleed air from the compressor of the engine is routed though the leading edges. It heats stainless steel strips and they will not allow the accumulation of ice. This requires lots of bleed air and that robs the engines of power and increases fuel consumption. It requires much more power than is necessary for the flight itself and typically is found in larger more powerful aircraft although it is also used in regional jets and many executive jet aircraft but sadly not all. Requiring more power means more expense to buy, greater expense to operate but greater safety is the prize. Other anti-icing options include, weeping wings which bleed glycol or other anti-icing fluids through tiny holes in a mesh leading edge, and electrically heated leading edge devices. The electrically heated leading edge devices will become more and more prolific once low weight high power electrical generators are introduced currently being developed for the newest transport category airliners.

Fortunately for jet operators, much of their flying time is above the weather including icing conditions but as many of the very light jets compete for scarce airspace and air traffic delays due to bad weather become more common, these low powered mostly de-icing equipped jets will suffer from accidents due to the limitations of this equipment. The propeller driven piston powered airplanes are simply doomed to suffer accidents in icing conditions because “certified for flight into known icing conditions” is a cruel hoax for which they are clearly ill-equipped. Small turbine propeller driven aircraft are equally hexed because their tiny engines just don’t have sufficient bleed air to do the job to inflate the boots under the most demanding of flight conditions.

The answer is straightforward. First, the Federal authorities must get their acts together and make a sensible realistic definition of “known icing conditions”. Second, the Federal authorities must ensure that manufacturers comply not only with the letter of the law but also the spirit of the law. If a manufacturer anticipates as it should that a “known icing” certified aircraft will be flown in lots of different icing conditions then it must ensure the aircraft will do it safely. Today that is not so. Third, the Federal authorities must mandate that all aircraft with a “known icing” certification be equipped with anti-icing equipment sufficient to prevent the accumulation of ice and that all power plants have sufficient reserve power to effectively operate this equipment. Fourth, the Federal authorities must carefully review prior known icing certifications and monitor new ones to ensure not that the aircraft meets the letter of the law but that it will be safe to fly in all reasonably anticipatable icing conditions. Under no circumstances should Federal authorities be allowing manufacturers to rewrite their flight manuals after certification to accommodate the reality of accidents in airplanes that never met the requirements in the first place.

Safe flight in icing conditions can’t be the luck of the draw, it must be totally predictable, repeatable and without chance. The only thing manufacturers have control over is to design and build in the capability of an aircraft to safely fly in icing conditions. A higher authority has control over the existence of and the severity of icing conditions that are likely to be experienced. Given man’s control over the former and his lack of control over the latter it is incumbent upon him, and well within the technology, to ensure that emergence safely from the latter is guaranteed.

COMPOSITE STRUCTURES FOR AIRCRAFT ARE NOT ALL THEY ARE ”CRACKED UP” TO BE

A recent NTSB Safety Recommendation should be of great concern to aircraft manufacturers, airlines and their passengers. It concerns the “disbonding” of the composite rudders on some A300 Airbus airliners. It seems hydraulic fluid delaminates the bonding agent and allows the plies of composite material to separate. The danger is that strength of the composite structure is compromised, such that it is no longer useful as an aircraft structure and can result in a catastrophic separation in flight.

Everyone loves composites these days. Why? Because they are light, rigid, strong and increasingly easy to build. They are stronger than their steel and aluminum counterparts and are infinitely lighter. Aircraft manufacturers, ever mindful of the needs of their airline customers, especially fuel costs, are trying to make structures lighter so less power and less fuel will carry the same number of passengers less expensively. Also, since large composite panels can now be made efficiently, small aluminum panels can be substituted with huge sheets of composite structure, cutting manufacturing costs and the price of the finished aircraft.

The rush to larger and more complex structures, however, must be tempered with the very high risk of in flight break-up and a deadly crash caused by unforeseen structural failure or disbonding from the ever present leakage of hydraulic fluid from the myriad of hydraulically operated systems in aircraft, like landing gear, flaps and flight controls. These systems, operating at thousands of pounds per square inch pressure, leak frequently, and a leak where fluid accumulates and remains for long periods can be deadly.

What’s needed is a substitute for the highly toxic, corrosive and composite destroying hydraulic fluid now in use, one that will not disbond composite structures. If this step is not taken at once, we are asking for trouble — and it will be big trouble. New aircraft are increasingly large, carrying more and more people. An Airbus 380 carrying 800 people cannot shed a major structure with impunity. Already the wing failed a critical ultimate load test, and the less than optimal results were double talked away by engineers. No amount of double talk will adequately explain to hundreds of families the industry’s failure in the face of this knowledge to make absolutely certain that hydraulic fluid doesn’t cause an airplane to crash.

Hopefully, and I am not optimistic, the pressures of competition will cause aircraft manufacturers in both hemispheres to address this deadly problem. They have been forewarned!

CESSNA 208 CARAVAN NEEDS CRITICAL “KNOWN ICING” IMPROVEMENTS FOR SAFETY

The Cessna 208 is a marvelous airplane for carrying lots of people and heavy cargo, but only in good weather. Flown in icing conditions the airplane is dangerous and has crashed thirty times, and nearly crashed many more. The NTSB has designated curing its dangerous history of accidents Public Enemy Number One. Nine people have been killed this icing season so far, and it’s only half over.

We have represented several families whose lives have forever been changed because of the Caravan’s poor performance in even light icing conditions, conditions for which Cessna Aircraft Company (the plane’s maker), and BF Goodrich (the designer and maker of the deicing boots) have said the airplane is suitable. In fact, it is not. The Caravan should not be flown in any icing conditions, and some of the operators refuse to dispatch it into any known icing weather.

The problems with the Caravan are simple. It is underpowered and, in fact, it appears to have the lowest power to weight of any turboprop single. That means it cannot climb above the ice and thus avoid it before its aerodynamics are so compromised it suffers a drastic loss of performance and control.

It has too much parasite drag, meaning there are so many unprotected surfaces that when ice collects, it seriously and quickly degrades performance to dangerously inadequate levels.

It has deicing boots that are simply inadequate to protect the wings and tail so dangerous ice accumulations even when the boots are used properly, quickly and dangerously compromise control and thus safe flight. Often there is insufficient margins to exit icing conditions safely and climbing may be impossible due to low power.

The Caravan uses engine bleed air to operate the cabin heat and the boots. It has no separate pump to operate boots like some other turboprop airplanes and has no water separator to keep moisture that collects in the boot inflation tubes from freezing and compromising the boot inflation. The bleed air extraction, together with the loss of power from deployment of the inertial separator designed to keep ice from damaging the engine compressor, drastically reduces the already underpowered airplane’s ability to exit icing conditions.

The aerodynamics of the Caravan also play a role in its inability to safely handle ice. Its horizontal stabilizer does not have ice protection to the tip and the elevator balance horn is entirely unprotected. The tail provides an up force, unlike most others that provide a down force. Thus, the top surface of the horizontal stabilizer is critical. Ice on this surface causes a pitch up, loss of airspeed, wing stall, tail stall, and drives the center of lift on the wing so far aft that regaining control at any airspeed is questionable.

The failure of the FAA to understand the aerodynamics of this airplane is unforgivable given the repeated concerns expressed by the NTSB and its own knowledge of the problems reported by pilots in Caravan winter operations.

Recent Safety Recommendations by the NTSB about the Caravan bring credit on that agency’s understanding that “something is wrong here” and that previous blame on pilots for accidents beyond their control is unfounded.

The Caravan is fundamentally a good design for fair weather flying. It should have had anti-icing equipment, not deicing boots that by design allow dangerous amounts of ice to collect before shedding and leave lots of ice as a residual of their operation. The Caravan should have had a cantilevered wing, instead of drag producing struts and, if cargo pod equipped it desperately needed, pod anti-ice protection. The powerplant is in need of twice the horsepower for this mission, and elevator balance horn anti-ice protection is vital.

The Caravan can be fixed and, if it had been fixed when the FAA first started to investigate icing incidents and accidents shortly after the aircraft was introduced, the airplane might have been well suited today for the all weather operations it is touted by Cessna to be capable. It is not, and the Randolph, Fry and Silvey families have suffered horribly, as have then ten little girls who have been left fatherless.

The FAA and the NTSB must do better. Twenty years have gone by since the first investigations and still no positive and effective efforts to fix the airplane. It is clear that at least the FAA lacks the technical expertise or will to understand the aerodynamics of the Caravan. At this late date, after three separate safety investigations, the FAA still thinks the bottom surface of the horizontal stabilizer is the critical lifting surface. It isn’t!

It is also unfortunate for Cessna, who has had ample opportunity to fix the airplane, yet still denies it has a problem. This is litigation driven no doubt so, instead of fixing it and avoiding other accidents, other tragedies for the victims’ families and other lawsuits for wrongful death, it denies the problem that everyone, including the federal authorities, knows about, and allows more accidents and more claims. Aside from the moral bankruptcy of such a position, from a purely economic standpoint, it is inexplicable.

There is hope, however. Others recognizing the problem have started addressing it themselves. Weeping wing TKS retrofits are now available to provide anti-ice protection. Larger and more capable powerplants are being STC’d by others for the aircraft and even a hot wing anti-ice system is being tested. Hopefully these non-Cessna designed and built modifications will save lives, but must be purchased at substantial cost by operators of these aircraft.

The icing accidents and incidents involving the Caravan have reached intolerable levels. Something must be done and done quickly if others are to be saved. After nearly forty years litigating airplane crashes, it never ceases to amaze me that aircraft manufacturers won’t listen. Airplanes always telegraph their intention to fail long before they suffer a fatal accident. Fixing the airplane before the first accident is the least expensive means to reduce the cost of air crash litigation liability, and fixing it after the first accident will guarantee that there will never be a claim for the same defect after the payment of the first one.

WHEN IT COMES TO AVIATION SAFETY, WHO IS REALLY TO BLAME?

The FAA … The Agency That Is Supposed To Protect Us

Why does it take an air crash to raise the public’s concern about aviation? Even though air travel is still the safest means of transportation (based on the percentage of fatalities compared to the number of people who fly), there are hundreds of accidents just waiting to happen … and US Air 1016 was one of them. The FAA has known, for years, about the dangers of wind shear during hazardous weather conditions, and in fact, has been installing special Doppler radar systems at busier airports. However, the FAA never moves quickly enough. Charlotte-Douglas International Airport doesn’t have their Doppler radar yet. The scheduled delivery for 1995 wasn’t soon enough to have protected the 37 killed last week. While the FAA is bogged down in bureaucratic red-tape of its own making, pilots, who are the ultimately responsible for the safety of the flight, are denied timely information that can help prevent accidents like the one in Charlotte. Unfortunately, the FAA’s ineptitude doesn’t stop there. All too often, the FAA knows about manufacturing defects that will clearly affect the safety and/or crashworthiness of airplanes. The FAA doesn’t do anything about those either, or it acts too late.

Between December of 1992 and December of 1993, 13 people were killed in two airplane crashes caused by hurricane force turbulence in the wake of Boeing 757 jetliners. The FAA knew, as early as 1989, that the 757 would, sooner or later, cost lives. Again, the FAA did nothing.

Why didn’t the FAA react? By mandating safe distances between aircraft, the number of flights leaving from and arriving at airports would be cut down, which would cut into industry profits.

In the early ’70s, the FAA was aware that the DC-10 baggage door had a design flaw. It did not act, and 350 people were killed in a Turkish Airlines disaster.

The FAA knew if it allowed Boeing Company to glue certain airliner sections together, they would have to monitor the long term effects. They did not, and the roof blew from an Aloha Airlines Boeing 737, while the side blew out of a Boeing 747. More fatalities resulted in both cases.

The FAA knew there were service problems with the engine attachment bolts on the Boeing 747. It did not act, and two engines came off an El Al 747, killing 45 people in the Netherlands.

The FAA has known for years about flaws in various general aviation aircraft — everything from pilot seats that slide suddenly rearward, causing loss of aircraft control, to undrainable contamination in fuel tanks which result in engine stoppage, to tails that fluttered off hundreds of times, killing hundreds of people, to engines used in helicopters which are so unreliable that the Justice Department sued the manufacturer for fraud in regard to the engine’s unreliability, while the FAA continues to certify the engine safe for flight.

The list goes on and on, but the one thing is clear. It is time to overhaul the FAA from the top down, and bottom up.

The people within the FAA who want to do their jobs and are interested in safety cannot because they are overruled by managers. People with the agency who want to change things to make the FAA more safety conscious are overruled by political considerations imposed on the FAA by influence wielded by the aircraft manufacturers — the same manufacturers the FAA is supposed to regulate.

There is even a product liability bill that would not permit the imposition of punitive damages against an aircraft manufacturer, if the FAA certified the aircraft before it was marketed. Though everyone in government calls the FAA incompetent, Congress still wants to make the FAA’s approval the difference between people being compensated and manufacturers punished, and their not being held liable at all.

The FAA has the responsibility to ensure the safety of flight and to promote aviation. Aviation does not have to be promoted anymore, but safety of flight needs a lot of work. The new FAA needs to have as its sole job the enforcement of existing regulations, the streamlining of regulations to make them more effective, and the enforcement of those regulations (for a change) against those responsible to make flight safe: the aircraft manufacturers who can make the airplanes safe.

While the FAA may not put time and money into forestalling accidents until there is a tragedy, the FAA is itself a tragedy. Somebody needs to do something about its many faults before more lives are tragically and unnecessarily lost.