Leaflet EHSIT Training Final

7/28/2019 Leaflet EHSIT Training Final

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saety

consiDerations

HE 1

TRAininG LEAFLETmETHODS TO imPROVE HELiCOPTER PiLOTS CAPABiLiTiES


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>> Saety considerations or helicopter pilots


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Training leaet >>

content

Introduction 5

Aim 5

.0 Degraded Visual Environment (DVE)

7 . Helicopter Handling Characteristic s. Pilot Capabilities

. Visual Cues

.4 Risk Analysis

.5 In Flight

.6 Loss o Visual Reerences

.7 Conclusion

.0 Vortex Ring State

. Conditions or Vortex Ring

. Eect o Vortex Ring

. Vortex Ring pilot recovery actions

.4 Vortex Ring avoidance

.0 Loss o Tail Rotor Eectiveness (LTE) 4

. When Does LTE Happen?

. How can LTE be avoided?

. Recovery rom LTE

4.0 Static & Dynamic Rollover

64. Static Rollover

4. Dynamic Rollover

4. Precautions

Pre-light planning Checklist


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>> Saety considerations or helicopter pilots


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Training leaet >> 5

Introduction

The European Helicopter Saety Implementation Team (EHSIT) is a component o the

European Helicopter Saety Team (EHEST). The EHSIT is tasked to process the

Implementation Recommendations (IRs) issues identied rom the research conducted by

the European Helicopter Saety Analysis Team (EHSAT) (see Final Report - EHEST Analysiso 2 2 European helicopter accidents ).

This leaet is the rst in a series o saety related leaets and publications aiming at

improving saety by sharing good practises. These leaets will be accompanied by

web based training materials including videos, which will be available reely to all pilots

in order to enhance ight saety by addressing recognised training related issues.

Aim

Data rom the EHSAT review conrm that a continuing signicant number o helicopteraccidents is due to pilot disorientation in the Degraded Visual Environment, Vortex Ring

State, Loss o Tail Rotor Eectiveness and Static & Dynamic Rollover. Thereore, the aim

o this leaet is to improve the saety o helicopter operations by providing pilots with

the relevant inormation or each o these topics in order to allow a basic understanding

o the causes, the prevention and the recovery actions thereby enabling pilots to make

better, more inormed decisions.

Document re.: Final Report - EHEST Analysis o European helicopter accidents (ISBN 9-90-095-7)


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6 >> Saety considerations or helicopter pilots


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Training leaet >> 7

A continuing signifcant number o accidents are

due to pilot disorientation in a degraded visual

environment (DVE). Research has demonstrated

the strong relationship between helicopter

handling characteristics and available visual cues.

This has clearly shown that there are likely to be visual cueing conditions, helicopter

handling characteristics and pilot capabilities which, although manageable individually,

can be predicted to be unmanageable when in combination.

Analysis indicates that any, or a combination o, the ollowing three scenarios could result

in a serious accident:

A Loss o control when attempting a manoeuvre to avoid a region o impairedvisibility, i.e. backtracking, climbing above or descending below the DVE.

B Spatial disorientation or loss o control when transerring to instrument ightollowing an inadvertent encounter with IMC.

C Loss o situational awareness resulting in controlled ight into terrain/sea/obstacles or a mid air collision.

1.1 Helicopter Handling Characteristics

The inherent instability o the helicopter is a major actor in such accidents. For small

un-stabilised helicopters, it is the pilot who has to provide the stability and he needs

visual cues to do so.

1.2 Pilot Capabilities

Whilst most pilots receive limited basic training in ight with sole reerence to instruments,

the competence in this skill can deteriorate rapidly and thereore cannot always be relied

upon to saely extricate the unprepared pilot rom an inadvertent IMC situation.

1. DegraDeD Visual

enVironment (DVe)


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1.3 Visual Cues

Evidence shows that or a signicant number o atal accidents the primary causal actor was

degraded visual cues. Common actors, which act to degrade the available visual cues, include:

A Low levels o ambient light leading to a general reduction in the quality othe visual scene and the available optical cues, e.g. at dusk/night.

B Reduced visual range and/or loss o sight o the ground/surace o the seadue to the eects o og or cloud.

C The presence o atmospheric haze or sun glare.D A lack o surace texture or eatures such as buildings, roads and rivers,

or lack o street lighting etc. when ying at night.

E A lack o texture on the surace o the sea/water, i.e. calm water.F Poorly delineated sloping or rising ground contours i.e. snowelds.G Misleading cues such as a alse horizon rom, or example, a distant row

o street/road lights.

H Obscuration due to precipitation or misting on the cockpit windows.

1.4 Risk Analysis

When planning a visual reerence ight 'with the surace in sight', there are a number o

obvious risk actors which should be taken into consideration prior to take-o:

The aircrat is certicated or VFR/VMC ight only. The pilot is not trained/current or instrument ight operations. The pilot is not trained/current in recoveries rom unusual attitudes. The navigation will be by map and visual reerence, perhaps with GPS backup.5 The ight is planned to take place at a height at which the surace cannot be

clearly dened.

6 A segment o the route involves over-ight o a rural, unpopulated area orlarge eatureless areas such as water, snow etc.

7 The ight is at night or in conditions o atmospheric 'gloom'.8 Flight at night when there is no moon, or the stars and moon

are obscured.

9 There are, or are likely to be, signicant layers o low level cloud en-route (4/8 8/8).0 The visibility is, or is likely to be, limited en-route, i.e. visual range at or close

to the minimum required or conducting a sae ight,(which may be signicantly

higher than the stated state minima).

There is a signicant probability o encountering mist/og/haze en-route. There is a signicant probability o encountering precipitation en-route.


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Training leaet >> 9

I these risk actors are considered as a risk assessment checklist, it can be seen

that the magnitude o risk increases with the number o risks 'ticked'. For example:

I risks to were to be ticked, this would only pose a normal, acceptable level

o risk provided that the ight were to be undertaken in good VMC conditions.

Ifrisks1to9areticked,experienceindicatesthatthe fght shold ot bedertake.

Risks7to12alladdtothetypeofconditionsthatwouldmakeitextreel

lkel that a plot wold be able to ata cotrol o the arcrats atttde

b vsal reereces aloe.

1.5 In Flight

Once a ight is underway other risk actors may come into play:

There is a low level o ambient light. There is no visual horizon, or the horizon is only weakly dened at best.5 There are ew, i any, visual cues rom the ground plane.6 Changes o speed and height are not perceivable, or only poorly perceivable

by visual reerence alone.

7 Reducing height does not improve the perception o the horizon or cues onthe ground.

8 The view rom the cockpit is obscured due to precipitation/misting.9 The cloud base is lowering causing an unintended descent to retain similar

orward visual cues.

These actors will add to the inherent risk o the ight already assessed by the risks

ticked prior to the ight. For example:

Even i only risks to were to be ticked prior to ight, the overall risk would

increasesignicantlywereanyofrisks13to19tobesubsequently

encountered en-route.

Risks13to19allpointtotheneedforextremecaution(i.e.gentlemanoeuvresonly!)

and seros cosderato shold be gve to teratg the fght ad

codctg a sae, cotrolled precatoar ladg as soo as s sae to do so.


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1.6 Loss o Visual Reerences

I external visual reerences are lost then to prevent spatial disorientation, a pilot will

need to transer his attention immediately onto the aircrat instruments and use them

to establish a sae ight prole. A rapid risk assessment, taking into consideration the

weather, terrain, aircrat limitations, uel and pilots capability is critical to a speedyestablishment o a nominated sae ight prole. This may require the pilot, once

established on instruments, to conduct a turn back, a descent or a climb to a sae

altitude or a combination o these.

1.7 Conclusion

Risk analysis and timely decision-making are essential tools to be used by the pilot

during both the planning and the ight stages. Constant updating and evaluation o all

o the available inormation should assist the pilot to recognize dangers inherent

to a degraded visual environment. This will assist the pilot to carry out the appropriateactions in order to prevent the situation rom developing into a critical stage or which

the pilot may not have the relevant skill level, capabilities and/or helicopter instrumentation

to cope with saely.


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Training leaet >>


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12 >> Safety considerations for helicopter pilots

Oten considered as the equivalent o the xed-wing stall, Vortex Ring is a condition o

powered ight where the helicopter settles into its own downwash. Consequently,

the Rate o Descent (ROD) will increase dramatically (typically, at least three times the

ROD beore entering Vortex Ring), or the same power setting.

2.1 Conditions for Vortex Ring

Vortex Ring is likely to occur when descending in powered ight at an airspeed below

30 Kts with a Rate o Descent (ROD) close to the main rotor downwash velocity.

Downwash velocity or induced velocity is dened as the airspeed o the airow drawn

down through the rotor disc (Froude ormula). The induced velocity is a unction

o the helicopter type and gross weight. For example, a three bladed helicopter with a

rotor diameter o 10.69m and a weight o 2,250 kg would result in an induced velocity

o 10 m/s (2000 t/min). Whereas, or a two bladed helicopter type with a rotor

diameter o 11m and a weight o 1,000 kg the induced velocity is 6.5 m/s (1300 t/min.).Therefore, although Vortex Ring State is shown to be dependant on the helicopter

type and weight, a commonly accepted unsafe ROD is considered to be in excess of

500ft/min.

2.2 Effect of Vortex Ring

Vibrationsasvorticesbreakawayatthebladetips

Lessresponsive(sluggish)pitch&rollcontrolsasaresultoftheunstableairow

constantly modifying the thrust and moment of control

Fluctuationsinpowerrequirement(torqueorMAP2) as the large changes in

drag cause thrust variations

AbnormallyhighRODasvortexdevelops,whichcanbeinexcessof3,000ft/min.

2.3 Vortex Ring pilot recovery actions

Recovery actions may be taken by cyclic and/or collective application. However, depending

on the rotor system, cyclic input alone could be insufcient to modiy the helicopter

attitude to gain airspeed. It is also possible to recover rom Vortex Ring by reducing the

collective to minimum pitch. However, the loss o height during recovery by collective

2. Vortex

ring State

2 Manifold Air Pressure


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Training leaet >>

pitch reduction is greater than the corresponding loss o height by cyclic input, which

is the result o the ROD in autorotation at low airspeed being very high.

Thereore, the ollowing recovery actions should be initiated at the incipient stage to

minimise the loss o height:

Applyapositiveforwardcyclicinputtoachieveanaccelerativeattitudeto gain airspeed

Ifanaccelerativeattitudecannotbereached,decreasecollectivepitchto

enter autorotation and then apply orward cyclic, as required to increase airspeed.

2.4 Vortex Ring avoidance

Since the recovery actions will entail a considerable loss o height, it is imperative

to avoid Vortex Ring especially when close to the ground. Thereore, a ROD in excess o

t/min. at an airspeed o less than 3Kts whilst in powered ight should be avoided.

Thereore, the ollowing operations should be conducted with great care:

Connedareasrecceandapproaches

Downwindapproaches

Steepapproaches

HoverOutofGroundEect(HOGE)

Lowspeedautorotationrecovery

Downwindquickstops

Aerialphotography

to exit Vortex ring

1. Apply a positive orward cyclic input to achieve an

accelerative attitude to gain airspeed.

2. I airspeed increases; recover helicopter when IAS

reaches Kt.

3. I airspeed does not increase; decrease collective pitch

to enter autorotation and then apply orward cyclic, as

required to increase airspeed.

Depending on rotor system recommended nose down attitude can vary


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14 >> Safety considerations for helicopter pilots

On a single rotor helicopter, one o the main unctions o tail rotor thrust is to control

the helicopter heading. I tail rotor thrust is insufcient, an unanticipated and

uncommanded yaw may occur. This phenomenon has been a contributing actor in a

numberofhelicopteraccidentsandiscommonlyreferredtoasLTE.

Forthepurposeofthisleaet,LTEisconsideredtobeaninsucienttailrotorthrustassociated with a control margin deciency which can result in an uncommanded

rapid yaw rate. This yaw may not subside o its own accord and i not corrected can

result in the loss o a helicopter.

3.1 When Does LTE Happen?

LTEismorelikelytooccurwhenthecriticalyawpedalisclosetothefulltravelposition.

The critical yaw pedal is considered to be the right pedal or clockwise rotating main

rotor systems and the let pedal or anti-clockwise rotating ones.

LTEisgenerallyencounteredatlowforwardairspeed,normallylessthan30kt,where:

Thetailnhaslowaerodynamiceciency

Theairowanddownwashgeneratedbythemainrotorinterfereswiththe

airow entering the tail rotor

Ahighpowersettingrequiresayawpedalpositionwhichisclosetoitsfull travel

Anadversewindconditionincreasesthetailrotorthrustrequirement

Turbulentwindconditionsrequirelargeandrapidcollectiveandyawinputs

The ollowing are some o the operations where pilots can typically nd themselves at

a low height, low airspeed and a high power setting, where the wind velocity is

difcult to determine and the pilot is oten preoccupied with positioning the aircrat or

thetask:

Powerlineandpipelinepatrolsectors

Externalload

Hoisting

Fireghting

Landingsitereconnaissance

Lowspeedaeriallming/photograph

PoliceandHEMS

HighDensityAltitude(DA)landingandtakeo

Ship-DeckLandingandTake-O

3. LoSS of taiL rotor

effectiVeneSS (Lte)


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Training leaet >> 5

3.2 How can LTE be avoided?

During ight planning pilots must consider the Rotorcrat Flight Manual, especially

regarding perormance in relation to the critical wind azimuths, the DA at which they

are operating, the helicopter All Up Mass (AUM) and ight characteristics.

During the ight, pilots should be constantly aware o the wind conditions and the

available tail rotor thrust margin, which is represented by the critical pedal position.

Whenever possible, pilots should avoid combinations o the ollowing:

Adversewindconditionsatlowairspeed

Uncommandedyaw

Largeandrapidcollectiveandyawinputsatlowairspeed

Lowairspeedightinturbulentwindconditions

3.3 Recovery rom LTEPilots should be aware that i they enter a ight regime where any, or a combination o

the above occur, they are entering a potential LTE situation and they must be able to

recognise the onset and commence the positive recovery actions without delay. Recovery

actions will vary according to the circumstances, i height permits, attaining orward

airspeed without increasing power (i possible reducing power) will normally resolve the

situation. Thereore, as these actions may involve a considerable loss o altitude, it is

recommended that pilots identiy a clear escape route in advance o the operations listed

above.

to exit lte

. Apply ull opposing pedal to the direction o turn

. Adopt an accelerative attitude to gain orward airspeed

. I altitude permits; reduce power


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4.1 Static Rollover

Static rollover occurs when the helicopter pivots about one skid/wheel in contact with

the ground to such an extent that the helicopters Centre of Gravity (C of G) moves

beyond the skid/wheel. Once the static rollover angle is exceeded removal of the

original force causing the roll will not stop the helicopter rolling motion. This typically corresponds to a roll angle in excess o 3 or most helicopters, SEE FiGuRE 1.

Critical Rollover Angle

The critical rollover angle or a helicopter can be described as either the maximum lateral

slope angle upon which the helicopter can land, yet maintain its main rotor disc parallel

to the natural horizon, or the maximum apping angle o the main rotor system. Typically,

mosthelicoptershaveacriticalrolloverangleof13to17andifitisexceeded,application

o ull opposite cyclic will not stop the helicopter rolling motion.

4.2 Dynamic RolloverThis generally occurs when a helicopter is taking o, landing or hovering with one skid/

wheel in contact with the surace. The helicopter may begin to roll about the point o

contact with the surace (pivot point). The pivot point could be or example a skid/wheel,

stuck or restrained to ground, ice, sot asphalt or mud. It could also be a skid/wheel

contacting a xed object/ground whilst hovering sideways or during slope operations.

Dynamic rollover can occur at roll angles ar less than the static or critical rollover angles.

4. static & Dynamic

rolloVer

FiGuRE 1

STATiC ROLLOVER

FiGuRE 2

LiFTinG TO THE HOVER


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Training leaet >> 7

Excessive application o collective in combination with a rolling motion about a skid/

wheel can result in sufcient roll momentum that ull opposite cyclic cannot counteract,

even beore reaching the critical rollover angle.

Liting to the Hover (SEE FiGuRE 2)

Collectiveisraisedandliftgenerated Therightskidisstuckandbecomesthepivotpoint

Leftcyclickeepsthedisclevelwiththehorizon

Asmallrollratedevelops

Dynamic Rollover (SEE FiGuRE 3)

Collectiveisraisedfurtherandmoreliftgenerated

Criticalrolloverangleisreached

Nomoreleftcyclicisavailabletolevelthedisc

Horizontalcomponentoftherotorthrustwilladdtotherollrate

Therollrateincreases

Corrective Action (SEE FiGuRE 4)

Lowercollectivetoremovethehorizontalcomponentoftherotorthrustin

an attempt to stop the roll beore the C o G is beyond the pivot point

Thehelicopterwillcontinuetorollduetoitsinertiaandmayrollbeyond

the static rollover angle i the collective is not lowered soon enough.

FiGuRE 3

DynAmiC ROLLOVER

FiGuRE 4

CORRECTiVE ACTiOn


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4.3 Precautions

Any change in lateral C o G will modiy the lateral cyclic requirementand availability

Always practice hovering Engine O Landing (EOL) into the wind

When hovering or taxiing close to obstacles / ground use extreme caution Whenever possible, slope operations should be conducted into the wind During take-o and landing, especially on a slope, all control inputs

should be made slowly, smoothly and gently; helicopter sideward motion

should be avoided

During slope operations i the upslope skid / wheel starts to leave the groundbeore the down slope skid / wheel, liting to the hover should be aborted

On landing, i the cyclic control limit is reached, urther lowering o thecollective may cause a rollover

When landing or taking o on a oating platorm that is pitching and / orrolling, extreme caution should be exercised


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imprint

Disclaimer:

The saety improvement analyses and recommendations produced by the EHSIT

are based on expert judgment and are supplementary to the ofcial reports o the

accident investigation boards (AIBs). Such recommendations, and the saety

improvement actions that may ollow, are solely aimed at improving helicopter

saety, are not binding and under no circumstances should be considered to takeprecedence over the ofcial AIB reports. The adoption o such saety improvement

recommendations is subject to voluntary commitment, and engages only the

responsibility o those who endorse these actions. The EHSIT accepts no

responsibility or liability whatsoever with regard to the content or or any actions

resulting rom the use o the inormation contained in these recommendations.

Picture credits

Cover: AgustaWestland / Inside ront cover: Eurocopter /

Page 4: Eurocopter / Page 6: Eurocopter / Pages 8 9: John Lambeth /

Page 11: AgustaWestland / Pages 16 17: Johathan Beeby

Contact details or enquiries:

European Helicopter Saety Team

E-mail: [email protected]

www.easa.europa.eu/essi

For a download o the Helicopter Prefight Planning Checklistplease visit our website:http://www.easa.europa.eu/essi/ehestEN.hmtl

Training leaet >> 9


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Helicopter ino

Type Registration Weight

Longitudinal Lateral

CG Take-of

CG Landing

CG Alternate

Fuel on board Fuel required Endurance

Tech. Log

Helicopter documentsto be carried

Original or copy o the Third party liability Insurance Certifcate Yes

Certicate o Registration Yes

Certicate o airworthiness (ARC) Yes

Original or copy o the Noise Certicate (i applicable) Yes

Original or copy o the Air Operator Certicate Yes

Radio licence Yes

Ops Manual / Flight Manual Yes

Hours required or task Hours beore next inspection / CRS

Conguration Equipment

Helicopter preligHt planning cHecklist >> p 2/2

uel

Basic or EmptyWeight

+ Vr uel ir uel

Fuel + Start-up + Start-up +

Crew + Taxi + Taxi +

Internal Load + Trip + Trip +

External Load + 5 % or 0 %contingency

+ Alternate +

T / O Weight 0 min res + 10 % contingency +

Trip Fuel - Discretion + 0 min res +

Landing Weight Total Ramp Additional +

Alternate Fuel - uel accorDing to Jar ops 3 Extra +

Landing Weightat Alternate

Total ramp

perormance class (i applicable)

Departure En route Destination

Max. take-of / landing Weight

Max. Hover Weight IGE

Max. Hover Weight OGE

OEI service ceiling

www.easa.europa.eu/essi/ehestEN.html


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Helicopter preligHtplanning cHecklist

type o ligHt Date brieing time

WeatHer at Departure point / en route / arriVal / alternate

Metar

TAF

Weather chart Signicant weather chart

Upper winds Freezing level Icing

Surace wind Sunrise time Sunset time

task

n Departure En route

Arrival Alternate

c d Call sign

DEP ENR ENR DEST ALT ALT

ATIS

GND

TWR

APP

INFO

nv d Departure En route

Arrival Alternate

afd DEP ENR DEST ALT ALT

h PPR / Landing approval

t Loading Start-up

T/O Land Duration

personal ino

Valid documentsto be carried

Pilot license and Medical cert. Yes

Type rating / IR Yes

Flight recency Yes

Passports or identity card Yes

www.easa.europa.eu/essi/ehestEN.html


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EuROPEAn HELiCOPTER SAFETy TEAm (EHEST)

Component o ESSI

Eropea Avato Saet Agec (EASA)

Saety Analysis and Research Department

Ottoplatz 1, 50679 Kln, Germany

mal [email protected]

OCT

2010

Documents

Leaflet EHSIT Training Final