www.pwc.com
BSEE
Aviation Safety Support
Services Contract - Final
Report
Brief For Helicopter Safety
Advisory Conference (HSAC)
HSAC Meeting
Houston, TX
October 21-22, 2015
Information contained herein is for the sole benefit and use of PwC's Client and the US Government.
Bureau of Safety and
Environmental Enforcement
• Promote safety, protect the environment, and conserve resources
offshore through regulatory oversight and enforcement programs.
• PricewaterhouseCoopers (PwC) was commissioned to conduct an
aviation safety study with the goal of reducing the risk of injury and
damage from OCS helicopter operations.
• PwC’s report is currently undergoing a 3rd party Peer Review and is
being discussed solely for the purpose of a courtesy review​. The
Report’s content​s ​are deliberative and pre-decisional​. Any comments
received will be addressed and treated as appropriate​.
Because this information has not yet been approved, it does not
represent an official​ Bureau​ finding or policy.
© 2015 PwC
Why Charter a Study?
Mishap Realities & BSEE Safety Culture
Since 1999, there have been 23 accidents in the Gulf of
Mexico of which 5 were fatal (22%), with 13 fatalities and 15
injuries. The leading causes were:
Engine related
Loss of control or improper procedures
Helideck obstacle strikes
Controlled flight into terrain
Other technical failures
Reflects proactive and collaborative BSEE leadership
culture & mantra of safety
© 2015 PwC
2
Study Team
Team PwC – 12 Key Personnel + Firm Leadership
(PwC, ABSG Consulting, HRS Consulting, & VectorCSP)
Project Leadership
Stu Merrill – Project Manager
Harl Romine – Deputy PM
Task 1
Smith Kalita
Ann Christoffersen
Task 2
Jeff Pettitt
Darrel Creacy
© 2015 PwC
Task 3
Butch Flythe
Task 4
Dan Deutermann
Task 5
Dave Hollaway
Jake Johnson
Task 6
Rex Hayes
Mike Stewart
3
Project Overview
BSEE commissioned the Aviation Safety Support Services project to
analyze aspects of aviation safety encompassing 6 task areas:
Task 1 – Develop Helideck Inspection Procedures, Guidance, &
Training Module.
Task 2 - Assess aviation fueling network for the OCS oil & gas
aviation support industry.
Task 3 - Study egress, water survival, personnel training, and
personal protective equipment.
Task 4 - Study available helicopter systems and equipment to
improve BSEE aircraft and passenger safety in OCS environment.
Task 5 - Assess the potential effects to helicopter operations of
methane and other combustible gases
Task 6 –Perform a comprehensive review of both domestic and
international
literature related to offshore aviation safety.
© 2015 PwC
4
Aviation Safety is Paramount
“The conclusions and
Regs &
Standards
Bench
Marking
Fuel &
Servicing
Aviation
Safety
PPE &
Survival
Operational
Hazards
Aircraft
Equipment
© 2015 PwC
recommendations generated in this
report are the product of extensive
aviation safety review. While
programmatic issues such as current
Federal regulations, DOI and BSEE
policy, workforce capacity, budget
constraints, cultural entrenchment, and
organizational change management
aspects were considered, the
overwhelming aspect of flight safety
dominates the analysis.
The consistent perspective conveyed
throughout this report is to enhance
safe mission performance for offshore
oil & gas aviation support.”
Final Report To BSEE
Unbranded Report – Commissioned by BSEE
BSEE is commissioning a Third-Party Peer review
The consistent perspective conveyed throughout this report is to
enhance safe mission performance for offshore oil & gas
aviation support.
92 Recommendations
…. And on to Task 5- Hazards Associated
with Combustible Gasses and Helicopter
Operations…
© 2015 PwC
6
Task 5 - Explore hazards of oil & gas flight operations
 Work centered on evaluating the engineering and scientific merit of
the proposed methane ingestion hazard. A first-of-its-kind study
addressed this issue through a systematic simulation of various
methane ingestion effects on three common turboshaft engines. The
mathematical engine models were derived from a combination of
reasonable parametric assumptions, aerospace engineering
expertise, and engine OEM proprietary technical data.
 Methane ingestion needs to be specifically targeted by each engine
manufacturer for engineering study and results provided to BSEE.
 The industry needs to adopt a much more conservative attitude
about helicopter operations in the OCS.
© 2015 PwC
Methane Ingestion Hazard
• Offshore Helicopter Mishaps (accidents
and near miss incidents)
• Baker, Shanahan & Haaland, et al (2011)
GOM Mishap Study
• 1983 – 2009 = 178 accidents (~7 year)
• 54 (30%) Involved Fatal Injuries (139)
• Predominant root cause was partial or total
loss of engine power (31% fatal, 71% nonfatal)
© 2015 PwC
Methane Ingestion Hazard
• Offshore Helicopter Mishaps
• Bell 407 at Ship Shoal 208H (2013)
• Bell 206-L3 at Main Pass 61A (2011)
• 9 other mishaps consistent with APG ingestion were
identified from 1992 - 2014
• NTSB Safety Recommendation to DOI, USCG, and
API to mitigate APG ingestion hazard
© 2015 PwC
Methane Ingestion Hazard
• BSEE Task 5 – APG Ingestion Hazard
• Conduct technical analysis of associated
petroleum gas (APG) hazard to rotorcraft
• Identify if each helicopter engine
manufacturer has a known percentage of
APG hazardous to operations
• Evaluate effect of ingestion of each
combustible gas on each helicopter at
anticipated concentration levels
© 2015 PwC
Methane Ingestion Hazard
• APG Flare System
© 2015 PwC
Methane Ingestion Hazard
• Gas Turbine Brayton Cycle
© 2015 PwC
Methane Ingestion Hazard
• Category B Departure
Wind
Critical Decision Point
Emergency Return
To Takeoff Point
CDP
Vertical
Climb
Rejected
Takeoff
Minimum
15 Feet
Pinnacle Takeoff
Helideck
Accelerate to Best Rate of Climb (Vy)
To Clear HV Diagram Restrictions
Minimum
35 Feet
Autorotation
Forced
Ditching
© 2015 PwC
Methane Ingestion Hazard
• Category A Departure
Accelerate to Best Rate of Climb (Vy)
When Clear of Obstacles
All Engines
Operating (AEO)
Climbout Path
Wind
Accelerate to
Takeoff Safety Speed
(VTOSS)
Critical Decision Point
Emergency Return
To Takeoff Point
CDP
Vertical
Climb
Rejected
Takeoff
Minimum
15 Feet
Pinnacle Takeoff
Helideck
Minimum
35 Feet
One Engine
Inoperative (OEI)
Climbout Path
Autorotation
Forced
Ditching
© 2015 PwC
Methane Ingestion Hazard
• Pinnacle or Confined Space Approach
High
Reconnaissance
Initial
Approach
Vector
Wind
Low
Reconnaissance
One Engine Inoperative
Before LDP
LDP
Landing Decision Point
Normal or One Engine
Inoperative
After LDP
Pinnacle Landing
Helideck
© 2015 PwC
Methane Ingestion Hazard
• Rolls-Royce Allison was only manufacturer with a
methane recommendation (CSL-1230 dated 19
September 2001)
• Applies only to M250 turboshaft engines
• Recommends a maximum methane/air mixture of
3% by volume.
• Will minimize to risk of methane igniting inside of
engine, outside of the combustion area (sic)
• Advises flying upwind and above “known” methane
vapor clouds
© 2015 PwC
Methane Ingestion Hazard
• UK CAP-437 Standards for Offshore
Helicopter Landing Areas (2013)
• Advises a 10% Lower Flammability Limit
(LFL) for Unignited APG (CAA 2008/03)
• APG is ~90% methane LFL is 4.4% by
Volume
• 10% LFL 4.4% x 0.1 = 0.44% APG by Volume
• Concentrations above 0.44% have potential
to cause compressor surge or flameout
• Could not determine how Rolls-Royce or
CAA determined these parameters
© 2015 PwC
Methane Ingestion Hazard
• NORSOK C-004 Helicopter Decks on Offshore
Installations (2013)
• Section 5 requires CFD analysis or wind
tunnel test for mitigation of APG and
temperature hazards
• Possible momentary stalling of compressor
due to sudden air density changes (2 °C
isotherm)
• Free airspace above the helideck should not
be exposed to > 2 °C temperature increase
• 10% LFL (0.44%) APG restriction
© 2015 PwC
Methane Ingestion Hazard
• TAMU Aerospace Engineering Study
Analytic investigation of
methane ingestion on
power output of three
turboshaft engines.
Assess the change in
engine operating point,
compressor stall, power
loss, and resistance of
fuel control units.
© 2015 PwC
Methane Ingestion Hazard
• TAMU Aerospace Engineering Study
Engine B
6A-1C
© 2015 PwC
Engine A
1C
Engine C
1A-1C
Methane Ingestion Hazard
• TAMU Aerospace Engineering Study
© 2015 PwC
Methane Ingestion Hazard
• TAMU Aerospace Engineering Study
© 2015 PwC
Methane Ingestion Hazard
• TAMU Aerospace Engineering Study
© 2015 PwC
Methane Ingestion Hazard
• TAMU Aerospace Engineering Study
Table 10
Real Cycle for Turboshaft Engine A
Without and With Methane Ingestion by Mass
State
Enthalpy, 𝒉
[kJ-kg-1]
Temperature, T
[K]
Entropy, s
[kJ-(kg-K)-1]
Pressure, p
[bar]
Without Methane Ingestion
H
H*
1*
2i*
2*
288.3
288.3
288.3
505.1
551.1
288.2
288.2
288.2
502.1
546.5
6.6608
6.6608
6.6666
6.6666
6.7545
1.0000
1.0000
0.9800
6.9580
6.9580
With 5% Methane Ingestion
H
H*
1*
2i*
2*
304.2
304.2
304.2
528.1
575.7
288.2
288.2
288.2
494.1
536.2
6.9047
6.9047
6.9107
6.9107
7.0031
1.0000
1.0000
0.9800
6.9580
6.9580
With 10% Methane Ingestion
H
H*
1*
2i*
2*
320.0
320.0
320.0
551.3
600.4
288.2
288.2
288.2
487.4
527.6
7.1486
7.1486
7.1549
7.1549
7.2517
1.0000
1.0000
0.9800
6.9580
6.9580
With 15% Methane Ingestion
© 2015 PwC
H
H*
1*
2i*
2*
335.8
335.8
335.8
574.5
625.1
288.2
288.2
288.2
481.7
520.3
7.3925
7.3925
7.3990
7.3990
7.5002
1.0000
1.0000
0.9800
6.9580
6.9580
Methane Ingestion Hazard
• TAMU Aerospace Engineering Study
Table 11
Real Cycle for Turboshaft Engine B
Without and With Methane Ingestion by Mass
State
Enthalpy, 𝒉
[kJ-kg-1]
Temperature, T
[K]
Entropy, s
[kJ-(kg-K)-1]
Pressure, p
[bar]
Without Methane Ingestion
H
H*
1*
2i*
2*
288.3
288.3
288.3
543.8
588.9
288.2
288.2
288.2
539.5
582.8
6.6608
6.6608
6.6666
6.6666
6.7471
1.0000
1.0000
0.9800
9.0160
9.0160
With 5% Methane Ingestion
H
H*
1*
2i*
2*
304.2
304.2
304.2
567.7
614.2
288.2
288.2
288.2
529.2
569.9
6.9047
6.9047
6.9107
6.9107
6.9956
1.0000
1.0000
0.9800
9.0160
9.0160
With 10% Methane Ingestion
H
H*
1*
2i*
2*
320.0
320.0
320.0
591.7
639.7
288.2
288.2
288.2
520.6
559.4
7.1486
7.1486
7.1549
7.1549
7.2439
1.0000
1.0000
0.9800
9.0160
9.0160
With 15% Methane Ingestion
© 2015 PwC
H
H*
1*
2i*
2*
335.8
335.8
335.8
615.9
665.3
288.2
288.2
288.2
513.4
550.5
7.3925
7.3925
7.3990
7.3990
7.4921
1.0000
1.0000
0.9800
9.0160
9.0160
Methane Ingestion Hazard
• TAMU Aerospace Engineering Study
Table 12
Real Cycle for Turboshaft Engine C
Without and With Methane Ingestion by Mass
State
Enthalpy, 𝒉
[kJ-kg-1]
Temperature, T
[K]
Entropy, s
[kJ-(kg-K)-1]
Pressure, p
[bar]
Without Methane Ingestion
H
H*
1*
2i*
2*
288.3
288.3
288.3
522.6
572.3
288.2
288.2
288.2
519.0
566.9
6.6608
6.6608
6.6666
6.6666
6.7584
1.0000
1.0000
0.9800
7.8400
7.8400
With 5% Methane Ingestion
H
H*
1*
2i*
2*
304.2
304.2
304.2
546.0
606.4
288.2
288.2
288.2
510.0
563.2
6.9047
6.9047
6.9107
6.9047
7.0176
1.0000
1.0000
0.9800
8.0000
8.0000
With 10% Methane Ingestion
H
H*
1*
2i*
2*
320.0
320.0
320.0
569.5
631.9
288.2
288.2
288.2
502.5
553.1
7.1486
7.1486
7.1549
7.1486
7.2670
1.0000
1.0000
0.9800
8.0000
8.0000
With 15% Methane Ingestion
© 2015 PwC
H
H*
1*
2i*
2*
335.8
335.8
335.8
593.2
657.6
288.2
288.2
288.2
496.1
544.7
7.3925
7.3925
7.3990
7.3925
7.5163
1.0000
1.0000
0.9800
8.0000
8.0000
Methane Ingestion Hazard
• TAMU Aerospace Engineering Study
© 2015 PwC
Methane Ingestion Hazard
• TAMU Aerospace Engineering Study
• Methane ingestion slightly reduces
temperature at the exit of compressor (2*)
• In all cases, the temperature at the compressor
exit is below the autoignition temperature of
methane (810 K)
• Even if temperature would exceed
autoignition, flow strain would prevent
methane ignition in the compressor
• Methane will NOT ignite due to adiabatic
compression in the compressor
© 2015 PwC
Methane Ingestion Hazard
• TAMU Aerospace Engineering Study
• Methane will ignite in the combustor sharply
increasing TIT
• Back pressure on the compressor upsets the
operating point beyond the surge line resulting
in compressor stall or surge
• Increase combustor pressure increases N1 and
N2 turbine speeds uncommanded by fuel
control unit
• Fuel control unit senses overspeed and
deschedules fuel flow causing power loss
© 2015 PwC
Methane Ingestion Hazard
• TAMU Aerospace Engineering Study
• Resistance to power loss depends of type of
fuel control unit, amount ingested, and control
inputs from pilot.
• Because effects are so rapid, insufficient
reaction time for pilot to diagnose or recover
during high power output flight regimes
(takeoff and landing)
• Pilot responds by initiating autorotation to
preserve rotor RPM
© 2015 PwC
Methane Ingestion Hazard
• TAMU Aerospace Engineering Study
Even small mass
fractions of methane,
as low as 0.4% by
volume, may cause a
serious power loss in
the representative
turboshaft engines
© 2015 PwC
Methane Ingestion Hazard
• API 2L-1 Planning and Designing Helidecks
© 2015 PwC
Methane Ingestion Hazard
• Task 5 Findings and Recommendations
• Less than one-half percent methane ingestion
may cause a mishap
• Mishap (near miss incident) data on APG
ingestion should be collected and analyzed
(SafeOCS?)
• CFD studies should be conducted on each
facility to determine risk (APG vapor cloud
propagation and 2°C isothermal line)
• HSAC RP 92-4 should be substantially revised
for hazard mitigation procedures
© 2015 PwC
Methane Ingestion Hazard
• Task 5 Findings and Recommendations
• Helideck should be universally considered
contaminated in certain wind directions and
magnitudes with designation of no flight zones
when flaring or venting APG
• Designation of no flight zones for each facility
• Helideck monitoring system (HMS) should be
installed to provide wind, temperature,
barometric pressure, and prevailing visibility
advisories (similar to UNICOM)
© 2015 PwC
Methane Ingestion Hazard
• Task 5 Finding and Recommendations
© 2015 PwC
Methane Ingestion Hazard
• Task 5 Findings and Recommendations
• Positive radio contact must be made to the
facility prior and advisory received prior to
approach or departure from helideck
• No fly azimuths should be provided on a facility
mimic at the HMS station.
• Facility personnel must be trained on aircraft
communications procedures
• Gas flow monitoring to provide real-time APG
outflow data to facility operations
© 2015 PwC
Methane Ingestion Hazard
• Task 5 Findings and Recommendations
• Hot flaring does not provide a greater level of
protection due to thermal effects on engine
• CFD should be conducted for all legacy
facilities for both unignited APG dispersion and
ignited 2°C isothermal line determination
• FADEC engines may be more resistant by must
be confirmed by empirical testing.
© 2015 PwC
Methane Ingestion Hazard
• Metocean Prevailing Wind Rose
© 2015 PwC
Methane Ingestion Hazard
• 20% LFL (Normal Cold Flare)
© 2015 PwC
Methane Ingestion Hazard
• 20% LFL (Unignited Blowdown)
© 2015 PwC
Methane Ingestion Hazard
• Visible Flare
© 2015 PwC
Methane Ingestion Hazard
• 2°C Isothermal Line (Normal Flare)
© 2015 PwC
Methane Ingestion Hazard
• 2°C Isothermal Line (Ignited Blowdown)
© 2015 PwC
Methane Ingestion Hazard
Questions?
© 2015 PwC
Contact Information
For more information about BSEE efforts concerning operational risk
management and aviation safety, please contact:
Brad J. Laubach
National Aviation Manager
Bureau of Safety and Environmental Enforcement
Phone: 703.307.4865
[email protected]
Mr. Steve Rauch
BSEE Aviation Safety Manager
[email protected]
(208) 867-6867
For more information about PwC efforts concerning operational risk
management and aviation safety, please contact:
Mr. Harl Romine
(703) 424-0252
[email protected]
© 2015 PwC
Mr. Scott Hale
(503) 918-3682
[email protected]
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