Report prepared for Department of
Conservation on the use of Robinson
helicopters.

Total Aviation Quality Ltd

 Contents
Introduction ............................................................................................................................................... 3
Terms and Abbreviations........................................................................................................................... 3
Purpose...................................................................................................................................................... 4
Assumptions and Limitations .................................................................................................................... 5
What is mast bumping? ............................................................................................................................. 5
Executive summary ................................................................................................................................... 5
Methodology ............................................................................................................................................. 7
Department of Conservation (DOC) Helicopter Operations...................................................................... 8
Health and Safety at Work Act 2015 (The Act) ........................................................................................ 10
Robinson Helicopter Corporation (RHC).................................................................................................. 10
New Zealand Civil Aviation Authority (CAA) ............................................................................................ 11
Transport Accident Investigation Commission (New Zealand) ............................................................... 12
Robinson helicopters: mast bumping accidents in NZ ........................................................................ 12
What is the TAIC Watchlist? ................................................................................................................ 13
US National Transportation Safety Bureau (NTSB).................................................................................. 14
Summary.................................................................................................................................................. 15
Recommendations................................................................................................................................... 17

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 Introduction
On 23rd December 2016, the Robinson Helicopter Company (RHC) produced its 12,000 th
helicopter at its facility in Torrence, California. The company produces three basic models –
two-seat R22, four-seat R44 and five-seat turbine-powered R66. The various models are used
extensively in New Zealand and throughout the world. There are 293 Robinsons on the New
Zealand register, as at 1/05/17, representing about 40% of the New Zealand civil helicopter
fleet. The type has been operated in New Zealand since the early 1980’s (CAA Occ. 06-663
R22 HLC)1 They are in use in a wide variety of tasks including pilot training, private and
syndicate ownership, commercial and tourism operations, external load, general farming and
agricultural operations.
On 31st October 2016, a Robinson R44 helicopter crashed while conducting a survey flight in
Glenbervie Forest near Whangarei. The pilot and a forestry contractor on board were killed.
Two days later, on 2nd November 2016, the Department of Conservation (DOC) issued a notice
suspending the use of all Robinson helicopters for the transport of DOC Staff, volunteers and
contractors. DOC’s decision followed the fatal accident in Whangarei, and took account of
the placing of Robinson helicopters on a Transport Accident Investigation Commission
(TAIC) ‘Watchlist’ just a few days previously (27 October 2016).
TAIC had placed the Robinson helicopter on its Watchlist following the release of two recently
published accident reports, [15-002] R44 IPY at Lochy River2 and [13-003] R66 IHU3 in the
Kaweka Ranges, released by TAIC on 25th August 2016 and 5th May 2016 respectively. Both
reports identified a mast bump event followed by an in-flight break-up.
DOC’s Director of Health and Safety, Harry Maher, said the decision was made to protect
DOC staff including volunteers and contractors working directly for DOC. Mr. Maher stated,
“The safety of our people is paramount so in light of the recent accident we are suspending
the use of these helicopters for operations where DOC staff, volunteers and contractors are
passengers.”
Because of the uncertainty of the cause of the Whangarei crash at that time and concerns stated
in the TAIC Watchlist, DOC’s notice of suspension read that DOC would review its position
as further information from CAA came to hand. On 1st December 2016, TAIC released an
‘interim factual report’ on the Whangarei accident stating that it was ‘very unlikely’ that the
helicopter had broken up in flight or that the cause of the accident was mast-bumping, but
that investigations into what the cause of the crash was, were continuing.
Note: At the time of writing this report another fatal Robinson helicopter accident report was
released by TAIC on 29 March 2017 [14-006] R44 HBQ4 in Kahurangi National Park attributing
the accident to in-flight break-up following a mast-bump event, killing the pilot.

Terms and Abbreviations
1

www.caa.govt.nz CAA Occ. 06-663 R22 HLC
http://www.taic.org.nz , [15-002] R44 IPY
3
http://www.taic.org.nz [13-003] R66 IHU
4
http://www.taic.org.nz [14-006] R44 HBQ
2

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 CAANZ
DOC
FAA
FAR
CFR
NTSB
CASA
ATSB
RHC
R22/R44/R66
Low-G
Mast bump
TAQ
TAIC
SA
SN
SFAR 73
HSW Act
PCBU

The following terms or abbreviations are used in this report:
Civil Aviation Authority (New Zealand)
Department of Conservation
Federal Aviation Administration (United States)
Federal Aviation Regulation (United States)
Code of Federal Regulations (United States
National Transportation Safety Bureau (United States)
Civil Aviation Safety Authority (Australia)
Australian Transport Safety Bureau
Robinson Helicopter Corporation
Three Robinson helicopter models in production and in use in NZ
Acceleration less than that due to the force of gravity. A feeling of weightlessness
Contact between the inboard end of a main rotor blade or the rotor hub and the main
rotor drive shaft
Total Aviation Quality Ltd.
Transport Accident Investigation Commission (New Zealand)
Safety Alert (Robinson Helicopter)
Safety Notice (Robinson Helicopter)
Special Federal Aviation Regulation No. 73 Robinson pilot safety awareness training
Health and Safety at Work Act 2015
Person conducting a business or undertaking (HSW Act 2015)

Purpose
This report responds to a Brief (or terms of reference) provided to Total Aviation Quality Ltd.
On 6th December 2016, DOC’s Director of Health and Safety, Harry Maher, commissioned
Total Aviation Quality Ltd. (TAQ) to provide independent advice on the Robinson helicopter
safety issue in order to inform DOC’s decision making process about future use of Robinson
helicopters carrying DOC staff. The Brief provided by DOC reads:
“DOC is the single largest hirer of helicopters in NZ. We spend around $15m per annum hiring
helicopters throughout the country, including the hire of Robinson helicopters.
In the context of a number of fatalities over recent years, there has been an increasing level of concern
in some aviation quarters relating to ‘mast bump’ accidents in Robinson helicopters in NZ. The
CAANZ and TAIC have both provided information and commentary on the issue, and several
communications of recent times have been specific about the mast bumping issue and potential
solutions.
The ‘Lochy River’ TAIC investigation (15-002) and the placing of the Robinson type on the TAIC
‘Watchlist” in October 2016 are particularly relevant to the matter. The flight profile associated with
many DOC operations, mountainous conditions, high winds and occasionally severe turbulence, are
the exact conditions identified by TAIC as being the most conducive to mast-bumping and in-flight
break-up.”
While the writer is aware that other organisations may have mirrored DOC’s decision and
suspended or banned the use of Robinson helicopters, this report does not extend to, nor has
it taken instruction from, any organisation other than the Department of Conservation.

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 Assumptions and Limitations
Because of the commonality of the design philosophy of the three Robinson helicopter models,
R22, R44 and R66, in particular the low inertia two-bladed semi-rigid teetering main rotors
with independent coning hinges, and the teetering cyclic control systems (both unique to the
Robinson helicopter), this report does not differentiate between the models.
The issue around concerns associated with the safety of the design and/or operation of
Robinson helicopters is extensively documented.
This report does not purport to cover all technical aspects of the design or of the operation of
Robinson helicopters, nor every aspect of the various documents to which it refers or takes
excerpts from.
Authorities such as the helicopter manufacturer (Robinson), US National Transport Safety
Bureau (NTSB), US Federal Aviation Administration (FAA), New Zealand Civil Aviation
Authority (CAA) and the NZ Transport Accident Investigation Commission (TAIC), are all
on record with their respective positions.
These authorities are all very well informed. However, apart from the apparently agreed fact
that Robinson helicopters can be susceptible to large, improper or abrupt control inputs
(Robinson Safety Notices SN 20 and SN 32)5 increasing the likelihood of mast bumping and
subsequent in-flight break-up, there is a divergence of opinions on why this is so.
The language used in this report is, as far as is practical, intentionally ‘non-technical’

What is mast bumping?
As the term recurs throughout all documentation on the subject, a brief explanation is
included for the sake of clarity. ‘A mast bump event is not the initiating cause of an accident.
It is part of the accident sequence’, Kurt Robinson CEO Robinson Helicopters Corporation.
The onset of mast bumping can be preceded by the helicopter entering a ‘low-G’ flight profile.
A ‘mast bump’ is a contact between an inner part of a main rotor blade or a rotor hub and the
main rotor drive shaft (or ‘mast’) during blade rotation. With a R44 blade passing the nose of
the aircraft 13 times per second, if one blade hub makes contact with the mast, the subsequent
events happen extremely quickly.
Mast bumping usually results in the helicopter breaking up in flight, which is almost always
fatal for those on board (RHC Safety Notice #11)6
What happens during the mast bump sequence is well understood. What is not well
understood, or in fact is in contention, is what the circumstances were during a flight that
created the conditions that induced the mast-bump.

Executive summary
Research in the preparation of this report has found opinions of the well-informed
organisations regarding the design and/or safe operation of Robinson helicopters to be
5
6

https://robinsonheli.com/robinson-safety-notices/ (RHC Safety Notices #20 & 32)
https://robinsonheli.com/robinson-safety-notices/ (RHC Safety Notice #11)

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 polarized. Robinson Helicopter (RHC) is of the stated opinion that the safety concerns
surrounding the phenomenon of mast bumping in their helicopters is attributable to
inappropriate or incorrect control inputs of inexperienced or poorly trained pilots under
certain flight conditions. In the company’s written response to the TAIC Interim Report on
the Whangarei accident [AO 2016-007]7 dated 30th November, RHC refers to previous New
Zealand accidents involving Low G mast bumping, saying ‘these appear to stem from certain
training, operational culture and regulatory elements unique to New Zealand’.
RHC Safety Alert8 issued 18th November 2016 gives the assurance that mast bumping
accidents are entirely avoidable if stated procedures are adhered to.
New Zealand CAA appears to agree with RHC that better training of pilots is the solution.
The following statement is made on the CAA website 9 “CAA considers that there is enough
evidence to conclude that the operation of Robinson helicopters may endanger persons or property if
pilots have not been properly trained in operation of the aircraft in certain conditions.”
CAA’s response to two TAIC recommendations resulted in changes to the Robinson Safety
Awareness training for R22 and R44 pilots in New Zealand10. However, by its own admission
(CAA letter to NZ Helicopter Assn. 2nd Feb. 2017), CAA believes these changes to the safety
awareness training alone will not necessarily produce guaranteed or immediate results. It
further states” the onus will remain on operators to operate the aircraft appropriately and to
demonstrate an improved safety performance.”
The US National Transportation Safety Bureau (NTSB) along with the NZ Transport Accident
Investigation Commission (TAIC), on the other hand, is on record as holding a different view.
Excerpts from a Special Investigation Report into Robinson Loss of Main Rotor Control
Accidents April 199611: Notation 6405B, with respect to testing and certification of the rotorhead design, in part states:
“The Safety Board is concerned that adequate testing may not have been accomplished during
certification to resolve possible adverse aerodynamic characteristics of the rotor and flight control
systems of both the R22 and the R44. The Safety Board is concerned that the stability of the R44 and
R22 main rotor blades may be compromised by an inherent rotor system design deficiency that may
allow loss of control of the rotor system when operating the helicopter within the currently defined flight
envelope and in a manner that would seem normal in other light helicopters”.
The NZ Transport Accident Investigation Commission, (TAIC) is unambiguous in its position
when on its website www.taic.org.nz it states12:

7

8
9

http://www.taic.org.nz [16-007 R44 ]
https://robinsonheli.com/wp-content/uploads/2017/01/sa_low_g_mast_bumping_accidents.pdf (RHC Safety Alert)
https://www.caa.govt.nz/pilots/pilots/robinson-helicopter-safety/ Implementation
https://www.caa.govt.nz/pilots/pilots/robinson-helicopter-safety/

10
11

12

http://www.rotorshop.com/sir9603.pdf Special Investigation Report into Robinson Loss of Main Rotor
Control Accidents April 1996:
http://www.taic.org.nz/Watchlist2016/RobinsonhelicoptersmastbumpingaccidentsinNZ/tabid/293/language/enUS/Default.aspx

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 “The Transport Accident Investigation Commission is concerned about the number of accidents in New
Zealand in which Robinson helicopters have experienced ‘mast bumping’. These accidents have raised
concerns about the risks of flying these helicopters in the mountainous terrain and weather conditions
that are common in New Zealand. Part of the problem is that the available evidence has not allowed the
circumstances and causes of all of these ‘mast bumping’ accidents to be fully determined.”
“Further research should be undertaken into the factors that can lead to mast bumping.”
While there is always room for better training to improve a pilot’s knowledge, skills and
understanding of helicopter dynamics and performance, there remains a strongly stated
contention on the part of the agencies (NTSB and TAIC) tasked with determining the
circumstances and causes of accidents and incidents with a view to avoiding similar
occurrences in future, that all circumstances surrounding flights that have resulted in mastbump accidents may not be fully understood.
Despite the stated opinions of both agencies, at the time of writing this report, neither the
helicopter manufacturer, RHC nor NZCAA have given any indication these concerns will be
further investigated.
In the words of one submitter “Despite the renewed emphasis on training, there has been
no attempt at an enduring solution that would either confirm or remove the alleged
uncertainties around the helicopter’s design”.
The knowledge around unexplained mast bump events is unchanged from when DoC
initiated their suspension in November 2016, with the exception that TAIC have subsequently
stated that one fatal accident (R44 Glenbervie Forest) is ‘very unlikely ‘to have been a mast
bump event, but that another (R44 Kahurangi National Park) has been confirmed as being a
mast bump event. Assuming DOC’s risk appetite is also unchanged since the issue of the
suspension notice, the validity for the issue of that notice remains.
TAIC’s statement13 that “Operators must select a type of aircraft suited to the risk profile of the
intended use” is inextricably linked to the DoC statement in their Brief provided to TAQ in
commissioning this report – “The flight profile associated with many DOC operations (mountainous
conditions, high winds and (occasionally severe) turbulence are the exact conditions identified by TAIC
as being the most conducive to mast-bumping and in-flight break-up.”

Methodology
Consultation
In the preparation of this report a number of industry participants with a declared interest in
the topic were consulted.
The Helicopter Association of New Zealand (HANZ) was advised, via Aviation New Zealand,
of the appointment of TAQ to provide independent advice to DoC and invited to make a
submission on behalf of its membership. HANZ through the Aviation New Zealand weekly

13

http://www.taic.org.nz/Watchlist2016/RobinsonhelicoptersmastbumpingaccidentsinNZ/tabid/293/language/enUS/Default.aspx ‘What is the solution’

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 Newsletter notified all recipients of the review and provided TAQ’s email address for
operators to make individual submissions. Three emails were received as a result.
In conducting the review the writer has sought the input of very experienced Robinson pilots,
two of whom have logged 16000 hrs and 13000 hrs on the helicopter type respectively. Their
considered and constructive views are that if the helicopter is flown within its design limits
by properly trained pilots it is a safe helicopter. Those views are respected.
Document review
Where available, links to documents reviewed in the preparation of this report are annotated
by footnote.

Department of Conservation (DOC) Helicopter Operations
Different makes and models of helicopters are used by DOC in a wide variety of roles,
including accessing some of the most mountainous and remote parts of the country.
DOC helicopter operations will, at many times, be conducted in geographical regions
conducive to the generation of turbulence. The country is mountainous and subject to
maritime climate patterns, as compared to a more benign continental climate. The presence
and magnitude of turbulence is unpredictable. It may not be present at the commencement of
a flight, but become prevalent to severe over the period of a flight or with a change in weather
or topography during the conduct of a given flight.
It is common ground throughout RHC, CAA, NTSB and TAIC documentation that the three
Robinson helicopter models have been shown to be susceptible to low G conditions and
subsequent mast-bump on entry into, or flight in, turbulence, particularly when lightly
loaded. This has resulted in:

•

Special training of pilots (uniquely mandated by legislation for pilots of Robinson R22s
and R44ss and not for any other helicopter model),
Additional cautionary limitations to airspeed (R44 and R66) for flights other than in
‘smooth air’,
The promulgation of a manufacturer’s Safety Alert recommending pilots slow down
during periods of distraction such as tuning radios or conducting conversations with
passengers,
The generation of two separate Robinson Safety Notices.

o
o
o

SN 11 advising pilots to take great care to avoid any maneuver that could result in a
low G condition – adding that low G mast bump accidents are almost always fatal.
SN 32 (the wording of which was revised in May 2013 and again in February 2016)
stating that flying in high winds or turbulence should be avoided.
SN 32 is supplemented by an instructional video placing further emphasis on the
susceptibility of the R66 when operated at light weights.

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 Curiously, a further Robinson Safety Notice (SN 44 issued Feb. 2017)14 warns that “carrying a
passenger in and of itself increases risk because passengers add workload and distractions.”
DOC is the single largest hirer of helicopters in NZ spending around $15m per annum on
helicopter hire. It must consider if the ongoing use of a helicopter type that attracts these
precautionary, or even corrective, measures is appropriate to the conditions likely to be
encountered in a flight profile typical of its operating environment, when alternative
helicopter types are available.

14

https://robinsonheli.com/robinson-safety-notices/ (RHC Safety Notice #44)

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 Health and Safety at Work Act 2015 (The Act)
This report is not required to comment at length on the HSW Act. However, some basics must
be stated for the sake of context. Under the Act, DOC as a PCBU, has the primary
responsibility for the health and safety of workers and others influenced by its work. The Act
states: All businesses must ensure, so far as is reasonably practicable, the health and safety of
its workers and any other workers who are influenced or directed by the business. (e.g. In
DOC context – its direct contractors and volunteers)
As a PCBU, DOC is required to identify and understand work-related health and safety risks;
particularly those that have the potential to cause people serious injury or illness. It is required
to do what is reasonable, what is practical and what it is able to do to eliminate or, where they
can’t be eliminated, minimise those risks.15

Robinson Helicopter Corporation (RHC)
The company manufactures helicopters at its base in Torrence, California. Various models of
the three basic types (R22, R44 and R66) are in common use in New Zealand and throughout
the world. All three types have a common two-bladed, semi-rigid teetering main rotor design.
The blades have independent coning hinges, a feature unique to Robinson [TAIC]16
The company is of the stated opinion that the safety concerns surrounding the phenomenon
of mast bumping in their helicopters is attributable to inappropriate or incorrect control inputs
of inexperienced or poorly trained pilots.
Notably, one NZ accident victim had 4,500 hrs helicopter experience with 2,145 on Robinsons
of which nearly 1,000 hrs were on R44s. Another (non-fatal), an ‘A’ Category helicopter
instructor had 7100 hours of which 1900 hrs were instruction.
In November 2016, RHC published a Safety Alert ‘Low-G mast bumping accidents’) giving
the assurance that mast bumping accidents are entirely avoidable if the following procedures
are adhered to:
o
o
o
o
o
o
o

Avoiding a ‘low G’ flight profile
Avoiding cyclic ‘push-overs’
Applying the correct recovery technique in the event of an un-commanded
low G situation
Do not over-react of use excessive control inputs in turbulence
Slow the aircraft down when flying in turbulence
Slow the aircraft down at any time the flight is for the purpose of training or
transition
Slow the aircraft down anytime the pilot’s full attention is not being applied
to flying such as when talking to passengers or changing radio frequencies.

Robinson’s Safety Alert advises pilots that if all the precursors to the mast bumping condition
are avoided, in-flight break up will not occur. Given the large number of Robinson helicopters
15
16

www.worksafe.govt.nz
http://www.taic.org.nz

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[14-006] R44 HBQ para 3.3.4 pg. 6
Page 10

 flying around the world that have not experienced mast bumping and resultant in-flight
break-up it is asserted that the conditions conducive to this phenomenon can be attributed to
only two things:
o
o

Environmental conditions e.g. turbulence and/or
Inappropriate pilot inputs to the aircraft controls

RHC President, Kurt Robinson, disagreed with TAIC findings in their report [AO 2014-006
R44 HBQ] where he is quoted, “I think the pilot was flying and doing something he shouldn’t have
been doing, unfortunately.” (Media report - Carla Penman Radio NZ 30th March 2017)17.
The position of Robinson is interpreted as being that the continued safe operation of their
helicopters in New Zealand and around the world is dependent on properly trained pilots
focussed on flying the helicopter and applying the correct control inputs throughout all flight
regimes and operating the helicopter within its flight limitations at all times.

New Zealand Civil Aviation Authority (CAA)
The CAA’s response to two TAIC recommendations resulted in changes to the Robinson
Safety Awareness Training in NZ to more fully align with SFAR 73 Robinson R-22/R-44 Special
Training and Experience Requirements mandated in the United States by FAA in 1995. Details of
the consultation and a full summary of the resultant changes implemented by CAA are
published on the CAA website.18
Key elements of the training include:
• A new syllabus of R22/R44 ‘Ground’ and ‘in-flight training’ is prescribed.
The training will be completed by CAA certificated Part 119 and 141 organisations, or operators who have
an approved Robinson safety course.
It will be delivered by suitably approved and qualified A or B-cat instructors.
A General Aviation examiner with Robinson safety awareness privileges must approve the A and B-cat
instructors delivering the awareness training.
The training will be required when new pilots are type rated.
Ongoing training will be required every 24 months.
The pre-solo dual requirements on the R22 and R44 have been raised to 20 hours.

Of particular note is that NZCAA has declined to accept the TAIC recommendation that the
improved Robinson Safety Awareness training requirements be extended to include pilots
flying the R66 model. CAA’s reply to this TAIC Safety Recommendation 002/16 is recorded
on the TAIC website stating: “The CAA’s position on this is that on the basis that the FAA has twice
rejected the inclusion of the Robinson R66 model in SFAR 73, the Director will not implement the
recommendation, but will continue to monitor advice from Robinson Helicopters and the FAA with
respect to the operation of R66 helicopters”. The status of this TAIC Recommendation remains
recorded as ‘Open’.

17

http://www.radionz.co.nz/news/national/327794/us-helicopter-maker-rejects-nz-crash-report

18

http://www.caa.govt.nz/pilots/pilots/robinson-helicopter-safety/
http://www.caa.govt.nz/assets/legacy/pilots/robinson_conditions.pdf

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 TAIC’s investigation into NZ’s only R66 fatal accident [AO-2013-003] para 1.3 suggests that
the R66 is as vulnerable as the smaller Robinson R22/R44 types to a catastrophic mast bump
under certain conditions. The R66 has the same main rotor system design as R22 and R44.
In a letter to the NZ Helicopter Association in response to a NZHA request asking CAA to
help remove Robinsons from the TAIC Watchlist on 2nd February 2017, CAA stated
“Implementing the recommendations will probably not be sufficient to remove the helicopter type from
the watchlist. It is likely to take some years of operating the aircraft without accidents attributed to
mast bumping as proof that the measures implemented have been effective. While the CAA can assist
through various regulatory activities, and recent changes to safety awareness training and the
Airworthiness Directive creating a yellow arc on the airspeed indicator for flight in turbulence are
examples, the onus will remain on operators to operate the aircraft appropriately and to demonstrate an
improved safety performance. “
In August 2016, CAA commissioned an industry-wide Helicopter Safety Survey. A total of
596 responses were received. In response to the question “How frequently did respondents
think helicopter performance limitations were exceeded; 13% of respondents thought
‘Frequently’ and 49% of respondents thought ‘Sometimes’19.

Transport Accident Investigation Commission (New Zealand)
The Commission’s role is to determine the circumstances and causes of accidents and
incidents with a view to avoiding similar occurrences in the future. (www.taic.org.nz).
Excerpts from TAIC website: Robinson helicopters: mast bumping accidents in NZ
What is the problem?
“The Transport Accident Investigation Commission is concerned about the number of accidents in New
Zealand in which Robinson helicopters have experienced ‘mast bumping’. These accidents have raised
concerns about the risks of flying these helicopters in the mountainous terrain and weather conditions
that are common in New Zealand.
Part of the problem is that the available evidence has not allowed the circumstances and causes of all of
these ‘mast bumping’ accidents to be fully determined.
…a significant proportion have been found to have occurred in “low-G” flight conditions. Low-G can
be caused by large or abrupt flight control inputs or by turbulence. The risk of mast bumping in
turbulence increases with high power settings and operating at high speed and light weight.”
What is the solution?
“Operators must select a type of aircraft suited to the risk profile of the intended use. Similarly, all
pilots must understand the helicopter’s operating limitations, avoid circumstances which could see
these inadvertently exceeded, and receive proper training in the causes, dangers, and prevention of mast
bumping, including in low-G conditions.”

19

http://www.aia.org.nz/site/aianz/2016%20New%20Zealand%20Helicopter%20Survey%20Results%20(1).pdf

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 What is the TAIC Watchlist?
According to its website, the Watchlist highlights the Commission’s most pressing concerns20.
Items make the Watchlist because they represent:
High social, economic, or environmental risk,
They highlight systemic issues affecting transport safety, or
It is an issue the Commission has raised as a result of an enquiry, but little has happened
as a result, and we (TAIC) believe we are likely to see a repeat occurrence.
When we see the same issue re-appearing and the lessons we have identified not being addressed, then
we will try to raise awareness of our recommendations by adding them to our Watchlist.
“The commission is not a regulator, policy-maker or transport operator. It can only try to influence
those that are.”
(Media briefing notes: Commissioner Stephen Davies Howard, Watchlist 2016).
On 27 October 2016, TAIC added matters regarding the safety of the Robinson helicopter to
its Watchlist saying:
•

Since 1996 TAIC and the CAA have investigated 14 mast bumping accidents involving
Robinson helicopters costing the lives of 18 people.
o [Note: Following release of the Kahurangi R44 accident report [A2014-006] this
number is now 15 accidents costing the lives of 19 people].

•

The rate of Robinson helicopter in-flight break-up accidents in New Zealand had not been
significantly reduced by the adoption of US FAA measures intended to help prevent such
accidents.

•

“Four of our earlier recommendations made as a result of Robinson mast bump accidents have
yet to be actioned. We therefore remain concerned that there is real risk that we will see more
of this type of accident.”

(Commissioner Stephen Davies Howard, Watchlist 2016).
TAIC, in its report AO 2013-003 R66 IHU para 1.7 states:
“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.”
TAIC recommendation 015/1621 [Status – Open]
On 27th July 2016, the Commission made a recommendation for the need for cockpit video
recorders and/or other forms of data capture in the cockpits of certain classes of helicopter to
address this safety issue.

20

http://www.taic.org.nz/Watchlist2016/TwomorepressingconcernsWatchlist2016/tabid/298/language/en-US/Default.aspx

21

http://www.taic.org.nz/OutstandingSafetyRecs/tabid/95/Page/1/Mode/null/Recipient/null/ImplementationStatu
s/Open/Keywords/null/IssuedDateOffset/0/language/en-US/Default.aspx

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 CAA responded that it is prepared to accept the recommendation. It will conduct a safety and
cost benefit exercise of installing flight data and/or cockpit video in certain classes of
helicopters. Given the timeframe of such a study is likely to be lengthy; the Director cannot
provide a completion date at this stage.
While the installation of data capture technology would be a valuable aid to any post-accident
investigation and subsequent prevention, this recommendation does not hold much
significance in the context of this report. Installation of data capture technology such as
cockpit cameras would not eliminate or minimise the risk of an accident occurring. Although
such data may well provide insight into the circumstances on-board that preceded a mastbump initiated in-flight break-up.

US National Transportation Safety Bureau (NTSB)
Much the same as the NZ TAIC, the NTSB is charged with determining the probable cause of
transportation accidents and promoting transportation safety (www.ntsb.gov ).
Excerpts from a Special Investigation Report into Robinson Loss of Main Rotor Control
Accidents April 1996: Notation 6405B, with respect to testing and certification of the rotorhead design, in part states:
“The Safety Board is concerned that adequate testing may not have been accomplished during
certification to resolve possible adverse aerodynamic characteristics of the rotor and flight control
systems of both the R22 and the R44”.
“The Safety Board is specifically concerned that the unique design of the R22 and R44 rotor system
may result in flight characteristics that are not adequately addressed by 14 CFR Part 27 certification
standards; Anomalies in the main rotor system or cyclic control in the cockpit may have gone undetected
during the original certification process”.
“The Safety Board is concerned that the stability of the R44 and R22 main rotor blades may be
compromised by an inherent rotor system design deficiency that may allow loss of control of the rotor
system when operating the helicopter within the currently defined flight envelope and in a manner that
would seem normal in other light helicopters”.
Note: This NTSB Safety Board report does not include reference to Robinson’s more recent
model, the turbine powered R66, as this model was introduced 15 years later in 2011.
However, the rotor-head design of the R66 is a growth variant of the design of the R22 and
R44.
All three Robinson types have two-bladed, semi-rigid teetering main rotors. The blades have
independent coning hinges, a feature unique to Robinson [TAIC AO 2014-006 R44 HBQ
Kahurangi para 3.3.4 pg. 6].

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 Summary
The following points are summarised in bullet point format for readability. No significance
should be attached to the order in which they are written.
•

DOC’s suspension of the carriage of DOC employees, contractors and volunteers in
Robinson helicopters is currently in place.

•

DOC’s notice of suspension reads that DOC would review its position as further
information (from CAA) came to hand.

•

At the time of this report no further information (from CAA) has come to hand
o One Interim report from TAIC has said a mast bump event was ‘very unlikely’
(R44 Glenbervie accident)
o Another final report confirmed mast bump and in-flight break did occur (R44
Kahurangi accident)

•

The suspension does not affect the use of Robinson helicopters for tasks where DOC
staff etc. are not carried e.g. external load ops or animal control where the shooter is
not a DOC person.

•

The suspension does not affect aerial spraying operations as the carriage of a passenger
(DOC employee or otherwise) is not permitted by CAA Rule 137 except where
operators are individually authorised in writing to do so by CAA for Wand spraying.

•

Kurt Robinson, CEO Robinson Helicopters, has attributed mast bump accidents in
New Zealand to ‘certain training, operational culture and regulatory elements unique
to New Zealand’.

•

Unexplained mast bump events resulting in in-flight break-ups are not exclusive to
New Zealand.

•

Robinson Helicopters is of the stated opinion that the safety concerns surrounding the
phenomenon of mast bumping in their helicopters is attributable to inappropriate or
incorrect control inputs of inexperienced or poorly trained pilots.

•

An RHC Safety Alert asserts that mast bumping accidents are entirely avoidable if the
certain procedures are adhered to.

•

CAA concurs with RHC in stating on its website “CAA considers that there is enough
evidence to conclude that the operation of Robinson helicopters may endanger persons or
property if pilots have not been properly trained in operation of the aircraft in certain
conditions.”

•

CAA has accepted a TAIC recommendation to improve training for all R22 and R44
pilots in New Zealand.

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 •

CAA has rejected a TAIC recommendation to mandate the same Robinson Safety
Awareness training for pilots of R66 helicopters.

•

A CAA letter to NZHA states it [CAA] believes that changes to the safety awareness
training alone will not necessarily produce guaranteed or immediate results. It further
states, ”The onus will remain on operators to operate the aircraft appropriately and to
demonstrate an improved safety performance.”

•

Out of 596 responses to a 2016 Industry-wide Helicopter Safety Survey, in response to
the question “How frequently did respondents think helicopter performance
limitations were exceeded; 13% of respondents thought ‘Frequently’ and 49% of
respondents thought ‘Sometimes’

•

TAIC have raised concerns about the risks of flying these helicopters in the
mountainous terrain and weather conditions that are common in New Zealand.

•

TAIC believe part of the problem is that the available evidence has not allowed the
circumstances and causes of all ‘mast bumping’ accidents to be fully determined.

•

TAIC also state they believe that “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.”

•

Despite the renewed emphasis on training, there has been no attempt at an enduring
solution that would either confirm or remove the alleged uncertainties around the
helicopter’s design.

•

There is no evidence that, with the currently available information, TAIC are going to
remove the Robinson helicopter from its Watchlist.

•

The US National Transportation Safety Board, has stated its concern that “the stability
of the R44 and R22 main rotor blades may be compromised by an inherent rotor system design
deficiency that may allow loss of control of the rotor system when operating the helicopter
within the currently defined flight envelope and in a manner that would seem normal in other
light helicopters.

•

This statement by NTSB is informative as it suggests firstly that it believes problems
may be evident when operating the helicopter ‘within the currently defined flight
envelope’, and secondly, that the same problems would not be encountered in other
light helicopters

•

Clearly the positions of the parties are divergent.

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Page 16

 •

DOC as a PCBU has, under the Health and Safety at Work Act 2015, obligations to
ensure, so far as is reasonably practicable, the health and safety of its workers and any
other workers who are influenced or directed by the business.

•

As a PCBU, DOC also has an obligation to identify and understand work-related
health and safety risks; particularly those that have the potential to cause people
serious injury or illness.

•

In this regard, DOC, as the purchaser of a service, is entitled to choose a service (or
product) which it considers to best meet its needs and is fit for purpose under all
conditions for which it will be used. While cost of the service or product will be a
consideration, it cannot be an overriding consideration

•

The reasons why some Robinson helicopters have broken up in-flight with fatal results
while many pilots have operated the same helicopter types in the same geographical
and environmental conditions for many years and many thousands of hours sees the
helicopter manufacturer and NZ CAA with views opposed to that of the agencies
tasked with determining the circumstances and causes of accidents and incidents with
a view to avoiding similar occurrences in the future.

•

RHC Safety Notices and Safety Alert advise that a pilot must be 100% focussed on
flying its helicopters. Pilots must minimise distractions such as reading charts,
programming avionics, or attending to passengers (SN 41) and slow down when retuning radios or having a conversation with passengers (RHC Safety Alert). In fact, SN
41 suggests that any avionics programming that takes ‘more than a few seconds’
should be done while on the ground.

•

While, during many flight profiles for which the Robinson helicopter was designed
and intended, it may be possible to comply with the Safety Alert and Safety Notice
recommendations, the same might not be so during a typical DOC operation flight
profile.

Recommendations
The terms of reference for this report do not require it to make recommendations.

John Fogden
1 May 2017

Total Aviation Quality Ltd.

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