Aircraft Accidents and Lessons Unlearned XII: Liberty Helicopters N350LH

As I’ve stated before, the most tragic result of a fatal accident of any kind, is NOT learning from a previous accident what could have prevented it.  The last few weeks, I have been discussing a complete lack of common sense in aviation.  I avoid recent accidents because they are still in investigation, i.e. the report has not been signed.  My weekly articles are often aimed at the obvious accidents; those that affect the airline industry, therefore the accidents that are noticed by the flying public because of the victim count being tallied by the media on a daily basis.  However, to ignore accidents involving General Aviation and Air Tours (Part 91) operators flying nine-or-less passengers would be to ignore a diverse group of aviators, a great disservice to us all.

Helicopter tour accidents are numerous; more occur than the general public knows about, simply because low fatality count accidents ‘fly’ below the media’s radar.  The first accident I investigated for the National Transportation Safety Board (NTSB) in 2001 was a tour helicopter where six perished and one was critically injured.  Since there was no definitive probable cause to the accident, no final word speaking to how the accident occurred and therefore how to prevent a repeat incident.  Air tour certificate holders continue to enjoy relaxed oversight by overwhelmed Federal Aviation Administration (FAA) inspectors.

On March 11, 2018, a Liberty Helicopters, Inc., a Eurocopter AS350B2, Registration number N350LH crashed into the East River off the shore of Manhattan (Accident number: ERA18MA099).  During an engine out event, the helicopter impacted the river’s surface and rolled inverted due to a failed inflation float.  In the commotion following the forced landing, the pilot escaped from the capsized helicopter, but five passengers perished while trying to escape their restraints.

As the NTSB continues its investigation into the events that led up to the accident, the obvious questions they ask will be ignored in this article:  Were the nitrogen bottles used for inflating the pontoons properly charged or maintained?  Did the pilot verify the pontoon bottles were reading correctly before flight?  Was the fuel cutoff switch properly guarded?  How much passenger movement was allowed in the cabin?

The major issue to be discussed in this Lessons Unlearned concerns, not the manufacturer’s installed restraints, e.g. seat belts, but the passenger harnesses installed as part of a Supplemental Type Certificate (STC).  An STC is a modification made to the aircraft, post-manufacture; it supplements the Type Certificate, which provides vital information pertinent to the equipment built into an airframe, engine or propeller.  The restraints were installed by the manufacturer; the harnesses were installed later.  The harnesses were part of a business decision to provide customers (passengers) the ability to see outside the helicopter for, e.g. photographing, without the side doors being in the way.  The harnesses also allowed the passengers mobility: movement inside the cabin.

Common sense can be a difficult concept; it becomes evident when looking at an Operator’s culture.  Allowing movement within a helicopter cabin subjects the passengers to several safety concerns; it also exposes the aircraft’s flight sensitive equipment to safety issues not present when passengers are restrained.

Let’s be clear: the helicopter in question: an AS350B2, has a small pilot/passenger area.  Movement by passengers in flight can pose multiple issues for aviation safety.  There are dangers, both internal and external, that demand passengers remain safely buckled in their seats; there are even better reasons for maintaining a safe distance between passengers and the helicopter pilot’s controls, from inadvertently manipulating flight critical devices.

The passengers are restrained two ways: seat belts and harnesses.  Since the door is off, the Operator deems the seat belts can be unbuckled to facilitate freedom of movement; the harnesses MUST be secured, yet allows the passenger to, e.g. hang their feet out the side or slide in a bench seat to enable changing one’s position from looking forward to facing the side.

Here lies the cause of the accident.

As reported in the NTSB Preliminary report for accident ERA18MA099 and the FAA Emergency Order of Prohibition Docket (EOPD) number: FAA-2018-0243, the surviving pilot reported, “when he reached down for the emergency fuel shutoff lever (FSOL), he realized that it was in the off position. He also noted that a portion of the front seat passenger’s [harness] tether was underneath the lever.”  Why the FSOL was not guarded against inadvertent actuation (such as the tether tripping it) is one MAJOR safety issue; this borders on utter recklessness; this point cannot be minimized.  The harness, however, is a concern in that very likely the fuel was shut off unintentionally and easily.  The harnesses, designed to give passengers freedom of movement, were the initial contributor to the tragedy.

One constant throughout aviation is that the pilot’s controls are off limits to non-flight crew persons, from the Cessna 150 to the Robinson R22 helicopter to the Airbus A380 to the Goodyear Blimp; no one – not one … single … person – aside from the pilots, should be able to influence the safe operation of any aircraft, deliberately or accidentally.  Not only did the STC’s installed harnesses allow the fuel to be shut off, but the pilot was unaware of the action until it was too late.

The harnesses, likely the accident’s cause, then became the instruments of the passengers’ deaths.

Before the flight, the pilot pointed out to the passengers that a knife was available to cut their harnesses in case of emergency.  Let me repeat that … A KNIFE WAS PROVIDED as a back-up to the normal releasing of the harness.  As described in the FAA EOPD, the harnesses’ lanyards are secured by screwing closed a locking carabiner, a locking loop, to the helicopter’s airframe.  The loop is inaccessible by the person wearing it because it is behind the person’s back.  The EOPD states, after the fact, that ‘A supplemental passenger restraint system [harness and carabiner] must not require the use of a knife to cut the restraint, the use of any additional tool or the assistance of any other person’.

This is how tragic the deaths were: a knife was provided to cut the restraints that were supposed to be quickly-released.  Not just one restraint, but all five.  How reckless!  In a cabin fire, the passengers would have burned to death.

Restraints, whether seat belts or harnesses used in, e.g. Coast Guard helicopters, are robust straps; they are designed to withstand heavy ‘G’ forces found in aircraft operations.  Under the best circumstances, they are hard to cut; under the threat of drowning, they are impossible for the average passenger holding their breath in freezing water.  Conclusion: the harness carabiner was inaccessible to the wearer; the strap was difficult to sever; the knife would have been up for grabs, if the wits of the drowning passengers even remembered to use it or they were conscious/injured to look for it or the knife hadn’t fallen to the river floor.  The water was dark, cold and situational awareness (inverted) worked against them.

So, what happened?  This is indicative of Safety becoming irrelevant … and not just for the engineer who wrote the STC.  Many people dropped the ball.  Engineers who write STCs are not perfect; they only can see the modification from one perspective – an engineer’s.  It is exactly why I found that the NTSB primarily using engineers as accident investigators to be a short-sighted mistake.

I’ve worked STCs before; I’ve even questioned STCs before.  An engineer draws the STC on a ‘drawing board’, away from the aircraft.  The STC can be written and approved well before the aircraft is modified.  This is evident when working on aircraft, where, e.g. slat actuators cannot be maneuvered out of the aircraft’s wing.

In 2003, I worked an accident in Bogota, Colombia; an STC (the aircraft was leased from a US-based airline) written for a DC-9 aircraft by a qualified engineer, was discovered to be cause of the loss of aircraft and crew.  Briefly, the STC ignored the need for cargo restraints to translate the G-force loads into the aircraft’s structure.  The modification placed new cargo restraints onto positions that did not translate the loads into the structure, but into the flooring below.  During a turn, the floor failed, capturing the control cables for all flight controls and engines.  The aircraft crashed out of control.

Did Liberty’s pilots not question the passengers’ freedom of movement during flight?  Did the pilots not voice concerns over unexpected flight issues with open doors, e.g. bird strikes, weather, or turbulence?  Were the pilots not worried about mid-air upsets that could ‘push’ a passenger into the controls?  Did the pilot group have issue with the front passenger’s harness tether being too long, that it could get entangled with the main and tail rotor controls or the fuel shut-off, as it did?

What about the mechanic who installed the harness STC or the Inspection Authority inspector?  Did Maintenance not question the carabiner/harness system?  What about employing a knife as a means to cut the strap in an emergency?  Was the Maintenance provider worried that the slack in the front seat passenger harness could foul the helicopter’s controls; interfere with the pilot?

There is no separation between aviation specialties; Pilots, Maintenance and Engineering are in this one together; they each are the second set of eyes to each other’s work.  No one gets to walk away and say, “That’s not my job.”  The Lessons Unlearned take away this week was that: First, an engineer designed a reckless system that killed five passengers who had no hope of escape.  Two, those with experience, who should have said something, did not.  Each specialty owns a part of this tragedy.  It’s why pilots, mechanics and engineers must not forget this.  No air operator is too small to be diligent.

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