Home' Greymouth Star : April 7th 2017 Contents Greymouth Star
10 - Friday, April 7, 2017
armers in the valley reported
no discernible wind. Without
wind, you do not get turbulence
and turbulence is often a factor
in helicopter mast-bump
crashes where a main rotor
blade can slice through the cabin or tail
Yet, there on a mountainside near
Queenstown, strewn among the trees lay the
wreckage. The helicopter had broken up in
flight. Two lives were lost.
It was a Robinson.
The company, founded by Frank Robinson,
made its first helicopter in 1979 and 12,000
more have since rolled off its production
lines. Robinson is acclaimed, the recipient
of the Daniel Guggenheim Medal for his
“conception, design and manufacture of
a family of quiet, affordable, reliable and
Yet, according to crash data, people are
dying in these helicopters at an inordinate
The families of those who died on the
mountainside say Robinson helicopters
have pushed too far towards lightness and
affordability for New Zealand conditions.
It is a vexing issue. Whether the high
accident rate is due to operator error, or
because the unique Robinson rotor design
makes them more prone to catastrophe
when things go wrong, or both, is a question
that carries obvious commercial implications
and an emotional load for those who are
grieving loved ones.
But officials expected to be dispassionate
also hold concerns. In a decision heard
around the world of aviation, New
Zealand’s Transport Accident Investigation
Commission (TAIC) last October put
Robinson helicopters on its watch list — the
highest alert it can give.
The commission’s role is to inquire into a
marine, rail or air incident when it believes
safety lessons can be learned. But it has
no power to compel entities to apply its
recommendations, and there is room for
doubt that the other aviation safety agency,
the rule-making Civil Aviation Authority
(CAA), sees eye-to-eye with the accident
Citing 14 mast-bumping accidents costing
18 lives since 1991, the commission called
for renewed testing of Robinson helicopters
(among other recommendations aimed at
promoting safe handling of the machines).
The commission’s action was described as
an “outburst ” in an e-mail exchange between
a staff member of Robinson Helicopter
Company and, surprisingly, a CAA official.
After Newshub published the e-mails, the
CAA said the comment was “ banter”.
The Department of Conser vation has
stopped its staff flying in the helicopters
(pending receipt of a report it has
commissioned), so have Tourism New
Zealand and TVNZ.
Mast bumping is contact between the
inner part of a main rotor blade or the
rotor hub and the driveshaft or “mast ”.
Helicopters are not yet required to have
recording devices and there is rarely
eyewitness testimony or other direct
evidence about what led to a mast bump.
Statements in investigation reports
about probable cause are essentially the
same: “ The divergence of the main rotor
from its normal plane of rotation for an
undetermined reason.” Many mast-bump
accidents are known to have occurred in a
low-G situation (a feeling of lightness or
weightlessness, like when a car speeds over
a hump). That can result from turbulence or
large or abrupt flight-control movements.
A review of a decade of helicopter
accident data released by the CAA under
the Official Information Act shows
Robinson helicopters are involved in a
disproportionate number of crashes.
Robinson helicopters make up 35% of the
New Zealand fleet but have been involved
in 49% of accidents in the 10 years to last
November, including 64% of fatal accidents.
Notably, all seven fatal mast-bump accidents
were Robinson aircraft.
California-based Robinson Helicopter
Company makes lower-cost, lightweight
helicopters. The smallest, the two-seater
R22, makes up 14% of the fleet and was
involved in 28% of accidents and 36% of
This model is the popular choice for
training (with more than half of all training
hours) and is flown by a higher proportion
of low-hour pilots. It is, depending on the
point of view, nimble or sensitive.
The four-seater R44, the most popular
model in New Zealand, makes up 20% of
the fleet, a similar proportion of accidents,
and 23% of fatal accidents.
There has been one fatal accident involving
the biggest of the Robinson stable, the five-
seater R66. There were six of these craft in
the country as at the end of last year.
All three models share the unique
Robinson rotor head design and have
all been involved in catastrophic mast-
bump accidents in New Zealand and
The potential for mast bumping is inherent
in all semi-rigid two-bladed main rotor
systems that teeter around a central rotor
mast. With 295 helicopters, Robinsons
make up three-quarters of helicopters with
teetering systems registered here. The others
are the Bell 206 (79), Bell 47 (seven), and
UH-1 Iroquois (10).
But only Robinsons have been involved
in mast-bump accidents here in the past
decade and the CAA confirmed only
Robinsons were involved in fatal mast-bump
crashes in the past 25 years.
The Robinson rotor head differs from
other teetering systems in that it has three
pivot points rather than one. The rotor
system is lighter and more responsive to
control movements but also to turbulence. A
mast bump is usually catastrophic.
Those who died that summer’s day
two years ago near Lochy River, a short
hop from Q ueenstown, were Stephen
Combe, 42, and student James Patterson-
Mr Combe had 4500 flight hours in
helicopters and was regarded by former
students inter viewed by investigators as “a
very thorough and professional instructor
and pilot ”. He flew Gazelle helicopters with
the British Royal Marines in the war in Iraq
and was awarded a “best overall pilot award”.
Mr Patterson-Gardner was a trainee with a
pedigree. His forbears include a World War
Two Spitfire pilot and a great uncle who
was a pioneer with NAC (now Air New
Zealand). His father, Murray “Mo” Gardner,
was an Olympic skier and also an aviator.
His mother, Louisa “Choppy” Patterson,
is renowned in the helicopter industry. She
is one of five pilots in New Zealand to
have gained a platinum safety award for 25
consecutive years without a serious accident.
Her company, O ver The Top, had a similar
Among framed certificates on the walls
of its Q ueenstown office is a Gold Safety
Award recognising 19 years of continuous
ser vice by the company without an accident.
The award covered the period ending 2013.
On another wall is the framed photograph
reproduced above. In February 2015, 13
months after the period covered by the
safety award, her senior pilot and her only
child died in a Robinson R44 operated by
The accident report concluded that
the helicopter broke apart in mid-air
when a main rotor blade struck the cabin
after a mast bump. It was flying across
mountainous terrain at relatively high speed,
estimated at 102 knots.
Mrs Patterson and staff flew into the
Lochy River area about 20 minutes after
the R44 broke up. They searched without
thinking about which way to hover. You
hover into wind but there was no wind,
she said. “ Without wind, you don’t get
Mrs Patterson suspects something
happened to the aircraft to cause it to
instantaneously roll to the right and mast
bump — a pitch link failure, a blade crack?
An early suspicion it may have been the
result of main rotor-blade fatigue was
not borne out by the investigation — a
metallurgist concluded that blade fracturing
was a result of the accident rather than a
The head of Robinson Helicopter
Company, Kurt Robinson, visited Mrs
Patterson last year. He believes it was the
result of pilot error.
“I do believe it was a very tragic training
accident and that the instructor did not
get back on the controls soon enough,” Mr
Robinson said from Torrance, California.
“They were flying through an area where
there was turbulence, a student pilot on
his second training flight, and something
happened. It was tragic but there was
nothing wrong with the aircraft.”
The finding of the investigation, however,
was that it was “as likely as not that the
aircraft had hit a pocket of light to moderate
turbulence”. The report was equally
inconclusive about who was on the controls.
An abrupt control movement (particularly
in turbulence) can result in a sudden roll to
the right and a low-G situation from which
recovery can be tricky and can result in mast
Mrs Patterson, whose company had
operated a Robinson helicopter without
incident for some years before the accident,
says her son was “a measured boy ” unlikely
to make rash control movements.
In her opinion, the aircraft is not fit for
purpose and should be redesigned. How
come, she asks, other types are not as
“The Robinson rotor head will mast bump
sooner than other types and the reaction
from mast bump will be much quicker and
more severe,” Tom McCready, an engineer
and veteran accident investigator, said.
In other helicopters, you may walk
away with a fright and a dented mast, the
former CAA investigator said. Mast-bump
accidents in Robinsons in New Zealand
have been catastrophic.
A new TAIC investigation is now under
way after the death of the sole pilot of an
R22 in Reefton last week.
Robinson Helicopter Company does not
believe there is anything wrong with the
design. Its view is these accidents can be
avoided by pilots following the flight safety
guidelines for these aircraft, and that has
also been the tenor of CAA’s safety training
The helicopter company has responded to
TAIC putting Robinsons on its watchlist
by posting safety alerts stressing what pilots
must do to avoid low-G situations that
could lead to mast-bumping, such as slowing
down to 70 knots when distracted and in
turbulence and to respond to buffeting with
gentle control inputs.
The commission, noting that the three
Robinson models share the same rotor
system, recommended that United States
safety authority, the FAA, “reinstate research
into the dynamic behaviour of the Robinson
rotor system under conditions of low-G”.
Mr McCready has attended about 30 fatal
accidents, done the Robinson factory course
for maintenance and made a study of the
“I ’ve worked on teetering systems since
1978. Of the helicopters with teetering
systems you will be in trouble in a Robinson
way before the others and you will have a
He is concerned the Robinson rotor head
has been “normalised” and many pilots are
unaware that it is “unusual”. If it was up to
him, he would redesign the head, he says.
Mr McCready points out that he has
concentrated on what happens when a mast-
bump occurs rather than the conditions or
type of flying that may lead to it.
A mast-bump could occur so fast, Mr
McCready says, an instructor may not be
able to recover the situation when a trainee
is flying. “ When it turns to sh—, it turns to
sh— very quickly.”
Robinson purposely built a helicopter for
the masses and its machines have a place,
Mr McCready says. It may be that the
helicopter is sometimes pushed beyond what
it is designed for.
The owner of a flight instruction company
that uses Robinsons, but who did not
want his name published, notes they were
designed as an executive commuter. New
Zealanders were the first to put a hook on
a Robinson. They are used for mustering
and deer recovery. “Kiwis being Kiwis have
taken it to a whole different level. In the
right hands they are capable of doing that,
but you just have to know where those limits
Back to Mr McCready. “ It is not a
big, tough helicopter. If you relate it to
motorbikes, which are also about balance
and power and handling, it ’s a scooter. I ride
a good 1200cc motorbike. They handle well,
have got good brakes, the power to get you
out of trouble, got all sorts of things going
for them. But a scooter does not.
“ You’re on a scooter and you get between
two logging trucks. Now relate the trucks
to mountains where it is windy. A lot of
accidents that have happened is not the
fault of Robinsons, but because they are
He says he believes there has been an
over-reaction to the helicopters being put on
the watchlist. “ They (TAIC) are giving you a
Kurt Robinson, who replaced his father,
Frank, as president and chairman of
the company in 2010, says placing the
helicopters on the watchlist was unfair
because it did not allow time for changes by
the CAA to the training required for pilots
of Robinson helicopters to take effect.
Trainee pilots now have to do a Robinson
safety refresher every three months, qualified
pilots every two years.
“I ’m hopeful now that will make a pretty
dramatic difference,” Mr Robinson says.
“ We have these helicopters flying all over
the world and we did see a higher incidence
in New Zealand. I think a lot of it is the
particular manner in which the pilots fly. ”
New Zealanders may be more inclined, he
says, to do a cyclic “pushover” that can risk
low-G, a manoeuvre banned in the United
States because it can induce mast bumping.
A Robinson aircraft is like a high-
performance sports car, he says. “ It needs to
be handled properly. If done so, in the right
hands, the aircraft performs beautifully. But
if the proper training isn’t done or if people
handle the aircraft incorrectly then, yeah,
you can get into trouble real fast.”
Mast-bumping is not the cause but part of
the accident sequence, he says. “ You’ve gone
Mr Robinson says he does not know
how Mr McCready reached his view about
the rotor head design risk. The Robinson
company had looked at it “a lot and we
can’t find anything to it. ” An FAA rotor
craft panel had looked at the Robinson
tri-hinge design in the 1990s and “explicitly
found that it makes no difference to the
susceptibility to low-G mast bumping”.
However, research into the dynamic
behaviour of lightweight helicopter main
rotor systems was not completed because it
was not thought safe to conduct flight tests
of the response to abrupt control inputs.
Georgia Tech School of Aerospace
Engineering subsequently worked on a
computer simulation model but ran out
of funds and the work was dropped in
1998 after the FAA decided it would have
“ limited application” and that “subsequent
validation . . . would involve extensive testing
with significant risk to flight safety”.
In calling for unfinished testing to
be reinstated, New Zealand’s accident
commission said it “is likely that mast-bump
accidents with Robinson helicopters will
continue to happen unless the dynamic
behaviour of the main rotor preceding such
a catastrophe is fully understood.”
It was suggested the litigious system in the
US would have seen Robinson Helicopter
Co sued out of existence had there been a
proven flaw in the design of its aircraft, but
also, conversely, the fear of retrospective
lawsuits might work against abandoning a
major aspect of its design, such as the rotor
Ilyas Akbari is a partner specialising in
transport accidents for Baum, Hedlund,
Aristei and Goldman, a Los Angeles law
firm that has acted in numerous actions
arising from helicopter accidents.
All of the firm’s cases involving blade
strikes were Robinson helicopters, Mr
“ Robinson Helicopters says it is
operational error, you shouldn’t be flying in
high wind areas. But in my opinion, a lot of
it also has to do with the design. If you can
make the blades more robust, in addition to
stiffening the vertical structure around the
main rotor mast, I think it would go a long
way to stabilising this helicopter.”
The blades had less mass and were more
flexible than comparable helicopters. “ When
you have less mass you have less ability to
recover,” Mr Akbari says.
“ I don’t know how much consideration
Robinsons has given that. Their position
is they have 30-million flight hours and
comparatively there are few accidents,
when in reality per thousand hours of flight
time they have by far the highest number
of deaths or crashes compared to other
According to data collected by the
independent Aviation Safety Network, the
four-seater R44, for example, has been in 95
accidents internationally since January 2015,
resulting in 58 fatalities. Twenty per cent of
those accidents, (making up three-quarters
of the fatalities), were recorded as arising
from unknown circumstances.
Mr Akbari: “One of the things that puzzles
me is that there are very experienced pilots
dying. It is one thing to blame the pilot but
at the same time a lot of experienced pilots
are dying in these helicopters.”
One of the most experienced Robinson
pilots in the world is Simon Spencer-Bower,
owner of Wanaka Helicopters. He is in his
50th year flying without mishap having
amassed 22,000 flying hours, 16,000 of
them in Robinson helicopters. His company
has five R22s and three R44s.
He says the debate about Robinsons can be
emotive and the reporting sensationalised.
“They don’t just break up in flight.
Someone has done something silly or is
operating in an environment they shouldn’t
be flying in.”
It is no different, he says, from a small boat
that operates perfectly well but should not
be taken out in a storm.
“Once you get to the mast-bump it is like
a car that has skidded. That ’s when you are
in serious sh—, so you don’t let it happen in
the first place.
“It’s like a car going over a hump. If you go
over fast you get that light tummy feel. Go
over slow you don’t get it. The emphasis in
the past was teaching people how to recover
from the low-G situation. I think there were
a few problems, so now the emphasis is on
recognising the conditions that are likely to
cause it and recognising the symptoms and
you don’t let it establish.
“ It ’s flying conser vatively. It occurs under
high power, that ’s why you are advised to
His view is shared by others spoken to,
notably veteran John Clements, who flew
in the war in Vietnam and is a former
owner of North Shore Helicopters. The
crash rate of Robinsons dropped markedly
after governors were fitted 20-odd years
ago, he says, and safety-awareness training
“ It went quiet about Robinsons. Then there
were a few crashes and all of a sudden there
is something wrong with the Robinson
helicopters. I don’t believe there is. I’m an
old-school pilot who thinks most accidents
are caused by pilots.”
In his lifetime of flying Mr Clements says
he has had only a few scares. “Each time it
was my own bloody fault ”.
Mr Spencer-Bower has experienced many
highs in his career, such as being awarded a
QSM in 2010 for ser vices to aviation and
being named flight instructor of the year by
the Helicopter Association International in
2015. Lows include the deaths in Robinson
accidents of three instructors who worked
Mr Clements currently works for a
company which does not operate Robinsons
but said he has no problem with them. “It ’s
a sensitive area and that ’s why I’m reluctant
to comment but I will say that if you had
most people learning to drive in Ford
Cortinas, then Ford Cortinas would have a
Graham Stott, Steve Combe and Jason
Wright died in accidents while flying with
students. Two involved mast bumps, the
third occurred practising recovery from a
loss of power.
There is a tendency when an experienced
pilot is on board, Mr Spencer-Bower says, to
say it must be the machine. “ I don’t consider
it (the helicopter) is a problem at all. I
consider it is the operator and the sooner
we get cameras or some recording device in
the machines, you are going to stop all this
speculation and innuendos. You are going to
have some facts.”
Robinson Helicopter Company hopes to
have a recorder ready by the end of the year.
It is adding an autopilot. “So in turbulence,”
Kurt Robinson says, “you can literally let go
of the controls and you will be fine.”
Louisa Patterson’s company has a recorder
ready for market. Called Eye in the Sky, it
records video, audio, speed, altitude, position
and information about pitch, roll and yaw.
Profits from sales are to go to the James
PG Foundation, named for her son, who
would have turned 20 last month.
A Reefton man died last week when his Robinson helicopter crashed. More than 20 years after United States safety
authorities began a special safety investigation into Robinsons, debate is again raging following a spate of crashes in
New Zealand. PHIL TAYLOR reports for the New Zealand Herald.
PICTURE: Otago Daily Times
Wanaka helicopter pilot and instructor Simon Spencer-Bower has achieved worldwide recognition.
Civil Aviation Authority investigators Tom McCready, left, and Marty Gambrill
examine the wreckage of a Robinson R22 helicopter which crashed into Bluff Harbour,
claiming two lives.
Are Robinson helicopters fatally flawed?
Links Archive April 6th 2017 April 8th 2017 Navigation Previous Page Next Page