Cessna Aircraft Company 208, VH-CYC

1. The pilots of CYC were conducting in-flight familiarization
   training using the emergency power lever. That procedure was not
   contained in the aircraft manufacturer's pilot operating
   handbook.
2. The engine manufacturer's documentation contained information
   on the use of the emergency power lever, which did not preclude the
   use of the emergency power lever for in-flight familiarization
   training.
3. The engine sustained a flameout at an altitude above mean sea
   level from which reignition of the engine was not successfully
   completed.
4. Erosion of the first-stage compressor blades would have reduced
   the aerodynamic efficiency of the compressor blades.

The pilots of CYC were conducting in-flight simulated engine
failure training, which involved activation of the emergency power
lever (EPL). The engine ignition switch was not in the ON position
during the initial operation of the EPL during this training. The
pilot's operating handbook (POH) contained a requirement to place
the engine ignition switch in the ON position during an actual
malfunction of the fuel control unit (FCU). However, because the
aircraft manufacturer only included requirements for an actual FCU
malfunction, the POH did not address the engine control settings
for training of this type.

The POH contained a caution which stated that the use of the EPL
was for emergency purposed only, and did not mention the use of the
EPL for in-flight or ground familiarization training. The engine
manufacturer's Service Information Letter (SIL) noted the use of
the EPL for familiarization training, while suggesting that this
training be completed on the ground. The discrepancy between these
two documents may have led to the flight crew's belief that the use
of the EPL for familiarization training in-flight was
acceptable.

Disassembly and inspection of the engine and fuel control unit
did not identify any anomaly of the engine that could have resulted
in the in-flight shutdown (flameout). However, the erosion of the
first-stage compressor blades to the engine manufacturer's maximum
service limits would have reduced the aerodynamic efficiency of the
compressor blades. This may have affected the optimum compression
ratio of the compressor section and resulted in decreased airflow
through the engine.

According to the pilots, the engine power setting was low
(reported at 55% Ng) at the time fuel was manually introduced using
the EPL. If the airflow through the engine had been affected by the
first-stage compressor erosion, the engine would have had a further
reduced airflow rate for that given power setting and excessive
fuel may have been introduced.

Analysis of the Engine Condition Trend Monitoring (ECTM)
information, which indicated higher parameters for engine fuel
flow, T5, and engine gas generator speed (Ng), should have alerted
maintenance personnel to the erosion of the compressor. The
inspection of the compressor completed 42.4 airframe hours before
the incident should have noted and recorded the erosion of the
first-stage compressor blades. Additionally, the ECTM information
indicated increases in fuel flow and Ng, with marginal decreases in
T5 temperatures. The decrease in T5 temperatures below the baseline
values was believed to be related to the insulation anomaly of the
two thermocouple probes.

A Cessna C208 aircraft, registered VH-CYC (CYC), with two pilots
on board, was being operated for pilot type endorsement training.
Air Traffic Control (ATC) had cleared the pilots to conduct upper
level air work between 4,000 and 5,000 ft above mean sea level
(AMSL) within a 5 NM radius of Green Island, Queensland. Following
the upper level air work, the crew requested, and were granted a
clearance for, a simulated engine failure and descent to 2,000
ft.

The pilot in command (PIC) reported that while completing the
simulated engine failure training, he had retarded the power lever
to the FLIGHT IDLE stop and the fuel condition lever to the LOW
IDLE range, setting a value of 55% engine gas generator speed (Ng).
The pilot under training then set the glide attitude at the best
glide speed (for the operating weight) of about 79 knots indicated
airspeed (KIAS). The PIC then instructed the pilot under training
to place the propeller into the feathered position, and maintain
best glide speed. The PIC reported that he instructed the pilot
under training to advance the emergency power lever (EPL) to
simulate manual introduction of fuel to the engine.

According to the PIC, he then noticed that there was no engine
torque increase, with the engine inter-turbine temperature (ITT or
T5) and Ng rapidly decreasing, and a strong smell of fuel in the
cockpit. While the pilot under training flew the aircraft, the PIC
placed the ignition switch to the ON position and also selected
START on the engine starter switch. He then reportedly placed the
EPL to the CLOSED position, the propeller to the UNFEATHERED
position and the fuel condition lever to the IDLE CUTOFF position
to clear the excess fuel from the engine. The PIC reported that
they then increased the aircraft airspeed to 120 KIAS, at which
point he reintroduced fuel into the engine by advancing the fuel
condition lever. He reported that following these actions, the
strong fuel smell persisted.

As the aircraft approached 1,500 ft, the PIC broadcast a MAYDAY,
informing ATC that they had a 'flameout' of the engine and that
they were going to complete a forced landing water ditching near
Green Island. While the pilot under training flew the aircraft, the
PIC placed the propeller into the feathered position, closed the
fuel condition lever to the IDLE CUTOFF position and turned off the
starter and ignition switches. They then completed a successful
landing in a depth of about 2 m of water near Green Island. The
pilots evacuated the aircraft without injury.

The aircraft, which sustained minor damage during the ditching,
but subsequent substantial damage due to salt water immersion, was
recovered to the mainland. Following examination of all connections
and control linkages, the engine was removed for examination under
the supervision of the Australian Transport Safety Bureau (ATSB) at
the engine manufacturer's overhaul facility. The engine trend
monitoring (ETM) data logger was also removed from the aircraft for
examination.

Engine information

The general condition of the engine was good except for
exfoliation corrosion of the magnesium and aluminium alloy
components as a result of salt-water immersion. The first-stage
axial compressor blades displayed significant erosion of the blade
leading edges at the blade root portion of the airfoil. The erosion
of the blades measured a maximum of .250 inch (.635 cm). According
to the engine manufacturer's maintenance manual, the erosion limits
of the compressor blade at the root was .250 inch without repair.
The eight engine thermocouple probes were also examined. Testing of
the probes indicated that they all passed the heat response test,
but two probes did not pass the insulation test. The engine
igniters operated satisfactorily when tested.

The engine fuel control unit (FCU) was removed to another
facility for disassembly and examination under ATSB supervision.
The examination of the FCU revealed no evidence of any internal
component failure or anomaly, which would have prevented normal
operation prior to salt-water immersion.

Engine temperature indicating system

The engine temperature indicating system consisted of a bus-bar
assembly, eight individual thermocouple probes connected in
parallel, a wiring harness incorporating a terminal block and an
adjustable trim harness incorporating a T1 thermocouple
probe.¹ The T1
thermocouple probe was connected in parallel with the T5 wiring
harness to bias the T5 signal and give the system a reference
point. The engine manufacturer's maintenance manual included a note
in the Engine Condition Trend Monitoring (ECTM) Shift Fault
Isolation Chart stating that the T5 indication usually decreased
when the thermocouple probes were unserviceable. The chart also
noted that:

If several probes are broken or damaged, the loop resistance
would not necessarily fall outside the allowable tolerance.
However, erroneous temperature indications could occur due to
reduced sampling.

An anomaly with the insulation of the thermocouple probes would
typically manifest itself in abnormally low temperature
readings.

Engine trend monitoring data logger

The ETM data logger recorded Ng, bus voltage, engine torque, T5,
engine shaft horsepower (SHP), fuel consumption, airframe hours,
engine total cycles, starts and duration and system exceedances.
This information was electronically stored on a removable data key.
Information stored on the data key could then be downloaded into a
computer. The pilot reported that the data key was installed into
the ETM display unit at the commencement of flight. However, after
the aircraft was recovered, the data key was not found.

After preservation, the ETM data logger was shipped to the
manufacturer for downloading. The manufacturer successfully
recovered nineteen exceedances covering a period from 1 January
2003 to 3 February 2004. The majority of those logged were
exceedances of propeller RPM and engine SHP.

Engine emergency power lever

The EPL, which was connected through linkages to the manual
over-ride lever on the FCU, governed the fuel supply to the engine
should a pneumatic section malfunction occur in the FCU. The EPL
permitted the pilot to restore engine power by activating the lever
to manually introduce fuel to the engine.

The aircraft manufacturer's Service Kit, SK208-142, provided for
the installation of mechanical devices allowing for the
installation of copper witness wire to the EPL. If the EPL was been
moved from the NORMAL position, the copper witness wire would
fracture and provide a physical indication that it had been
activated. The installation of SK208-142 was not mandatory for
Australian registered aircraft. However, the requirements of
SK208-142 had been complied with on the aircraft.

Cessna Alert Bulletin, CAB01-15, included a requirement to
ensure the fitment of the copper witness wire to the EPL of all
aircraft that had SK208-142 installed. Compliance with the
requirements of CAB01-15 was not mandated for Australian or United
States (US) registered aircraft. According to the flight crew, no
copper witness wire was installed on the aircraft at the time of
the occurrence.

The aircraft maintenance manual stated that if the EPL witness
wire was broken or missing, a determination was to be made as
required by the engine maintenance manual, to assess if the engine
limitations had been exceeded.

The aircraft manufacturer's information on the operation of the
EPL stated that the use of the EPL was for emergency purposes only,
and contained cautions about the use of the EPL for any other
purposes. Further information about the aircraft manufacturer's use
of the EPL is contained in appendix A.

The engine manufacturer's Service Information Letter (SIL)
Number PT6A-053R2 addressed the use of the EPL. Although it also
stated that the EPL was for emergency purposes only, it mentioned
the use of the EPL for training purposes under supervision to
maintain emergency practices proficiency. It included a note which
suggested that familiarization training using the EPL be conducted
on the ground. Further information on the operation of the EPL is
contained in appendix B.

The pilot reported that, based on the reference to
familiarization training in the SIL, he considered that the use of
the EPL for in-flight familiarization training was acceptable.

Civil Aviation Regulation 1988, Part 50E addressed inconsistent
requirements relating to aircraft operation and maintenance. Part
50E noted that by order of priority, the aircraft manufacturer's
requirements superseded the requirements of an aircraft component
manufacturer such as an engine manufacturer.

Recent engine maintenance

There were no engine logbook entries concerning engine
compressor erosion. Engine compressor washes had been completed on
a periodic basis as required. Civil Aviation Safety Authority
requirements for the aircraft are contained in appendix C of this
report. Engine trend data for the aircraft's engine are contained
in appendix D.