#exploding helicopters

Considering aviation was born in the USA, consider how the FAA reacts to Boeing’s continued failure to locate the problem to fix.   Did an entire 787 fleet have to be grounded because of one small fire in an unoccupied plane and a SOME smoke in another, from which passengers had to be evacuated? Certainly there are some problems with this newly designed airplane, which may still be on what the aviation people call the "learning curve," but so far no injuries, no deaths.     Now comes the news it wasn’t the battery.  Planes still grounded. Onward.     Contrast this with very same FAA which has over 20 years, taken pains to completely ignore one  of the most dangerous fleets of aircraft flying.  That would be the low cost, minimum design helicopters, made in and shipped to customers all over the world by an American company.   This America company now claims to be one of the largest helicopter manufacturers in the world, and reported record sales last year. The company boasts that 70% of its products are sold to overseas customers.       Two of its models, a two place and a four place have at least three serious built-in design flaws that have brought dozens, if not hundreds of these aircraft out of the skies, or have caused to burst into violent flames in minor impacts, or even rollovers.     Usually with total fatalities and or serious injuries.     There are some statistics on these incidents kept by the NTSB, and the NTSB has criticized these design flaws a numerous times.  But the FAA simply continues to ignore the entire issue.   The first problem is probably the most deadly: the propensity of the rigid metal tank fuel tanks and fuel lines break or rupture in a relatively low-impact,low G -force incidents.     The tanks are located directly above the passenger compartment and next to the high RPM mast, and quite near the red hot components; engine and transmission.   If a fuel tank or line is breached, it takes just seconds for escaped aviation fuel to find its way to the hot components. Same with rigid fuel lines.  Fuel can even escape from impact forces on an unbreached tank due to hydrostatic pressure.  Then, bang.  The entire mess pours into the passenger compartment.   In a matter of seconds bodies are reduced to "4th degree" burns and charring.     Avivation was born in the USA.  The FAA has done nothing about this.     Eventually, pressured by repeated multi-million dollar lawsuits and some strong government investigations and bulletins from overseas air authorities, the manufacturer finally came up with a long over due retro fix: replace the rigid tanks with flexible bladders and include in fuel lines, breakaway failsafe closures. Voila.  Fire resistant fuel system 101.  The company is now scrambling to get older aircraft owners to order and install the replacement kits. At owners expense.   As of 2010, the company changed the design for its new models, but according to the air authorities of one country, as of last count, only about 10% of the old fleet has been retrofitted.  This means as much as 90% of the flying public and crew, remain at risk.  At least in those areas.   We note the fire resistant design and flexible bladder technology for helicopters has been around for many years. We also note the military will not accept a machine without such, and has probably had that policy since the Viet Nam war, if not before.   The second problem is known by the term "debonding."  This means is that the rotor blade of either the two or four place model, suddenly and without warning, simply comes apart mid-air.  The skin, or thin metal cover of the blade quite literally "debonds" separating or delaminating from the strut to which it was glued. The naked blade now stops flying or providing lift, and flails wildly.     Usually the blade strikes some part of the helicopter or rips through the cabin.  The cause of the debonding is either one or both of a failure of the bonding agent, called "cohesive" or “adhesive" failure.  The short version is: the "glue" wears out.  Worse, in the certification process of the blades, no testing was ever done to determine how long the "glue" would last or hold.   No one knows when the glue might be expected to wear out.   The FAA the faa never required such testing or quality control measures.   The helicopter company is now busy here replacing blades almost 24/7.     What is the FAA doing?   Thanks for asking.  Not a thing.     The third problem uncovered, at least today, is their “mast bumping” phenomena. Unlike most small utility helicopters, these helicopters use only a two-bladed rotor, which has to in effect, balance at the top of its mast, in a teeter totter fashion.     One blade goes down, the other has to go up. This is called "underslung" and differs markedly from the technique used in other helicopters where each blade, usually at least three,  are independently bolted to the mast, so any up down motion in rotation is far away from the mast.     The "mast bump" comes in a situation where the helicopter, for whatever reason, goes into a "negative G" situation. This is similar to what one would feel in roller coaster that came to the top of the run at high speed, over top, and started down. that momentary lift, when one feels the seat seem to drop out from under, is negative G.   Negative G can be induced by control inputs, turbulence, coming over the crest of a hill and other maneuvers. Negative G is not uncommon for helicopters. Three blades, or non teeter-totter designs handle Negative G quite well.  But in the two-blade teeter totters, the action of the physical forces can cause the rotor to "unload" that is stop providing lift and the rotor blades to move away from the fuselage, since both are then "floating" in a negative G configuration.  The hull then rotates (rolls) away from the plane of the rotar, the rotating blades, not generating any rotor thrust or pulling the hull,  then swing closer and closer to the mast and the fuselage, until one of the blades actually strikes the mast (think massive "droop" of the blades).   When this happens, if the crew is lucky, the blade may be only damaged, and they may be able to land it safely. If not, the blade will detach, and hurl itself into the boom, the tail rotor, or the cabin.   All three of these conditions are very dangerous and can occur in seconds Without warning.  The manufacturer in its "safety bulletins" and publications, does talk about bumping and inspecting for worn blades (we have never found any warnings about the fuel system or the fire propensities.  The only mention is the retrofit option "to be safer," or some such) in its materials.  But in our opinion ALL these dangers are seriously understated and downplayed.   Back to the FAA.   The FAA has never issued an Air Worthiness Directive (AD) nor come close to grounding any of these helicopters.  See no evil, hear no evil, and certainly speak no evil. As we mentioned earlier, any and all pressure has come from aviation authorities outside the United States or in some court cases.   Many if not most of the accidents occurring overseas, which indeed are the majority (remember the 70% figure), can not stay in the United States courts even if the families or survivors seek redress here, where the machines are designed and made.     The American manufacturer has successfully HAD claims dismissed in U.S. courts stating the U.S. where these helicopters are manufactured, is not proper jurisdiction.   The American manufacturer claims the U.S. is an "inconvenient forum" for hearing cases involving American manufactured products.  The American manufacturer claims cases should go to the courts of the country the domicile of the victims or where the accident occurred.   Thus “Made in America” doesn’t mean “Accountable in America” as the manufacturer spends enormous sums to convince U.S. courts not to be held accountable.  Meanwhile, sales and profits, soar, unfettered by safety concerns.   In most all such cases, nothing is every heard again about that accident, legally speaking. There is no practical way to mount, finance, or prevail in this type of case in a non-US court.   Onward.