Aviation safety investigations & reports

Loss of control and collision with terrain involving Angel Aircraft Corporation 44, VH-IAZ, near Mareeba Airport, Queensland, on 14 December 2019

Investigation number:
AO-2019-072
Status: Completed
Investigation completed
Phase: Final report: Dissemination Read more information on this investigation phase

Final Report

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What happened

On 14 December 2019, two pilots were conducting a private flight in an Angel Aircraft Corporation Model 44 aircraft, registered VH-IAZ, at Mareeba, Queensland. An instructor seated in the right pilot seat was conducting a flight review of the pilot (and aircraft owner) in the left seat.

The aircraft took off from Mareeba Airport at 1058 Eastern Standard Time,[1] after which witnesses reported hearing one of the engines hesitating and backfiring, accompanied by a sooty smoke trail from the right engine. The aircraft operated in the training area until returning to the airport circuit area at 1112. Witnesses observed the aircraft touch down on the runway, accelerate and take off again. After take-off, the aircraft climbed to about 100-150 ft above ground level before entering a right descending turn. The aircraft was airborne for about 20 seconds before witnesses observed it rolling rapidly to the right and impacting terrain in a cornfield 475 m north of the runway. The pilots sustained fatal injuries and the aircraft was destroyed.

What the ATSB found

Based on the witness reports of abnormal engine sounds and because the instructor had planned to conduct a simulated engine failure after take-off, the ATSB assessed whether the accident occurred following a simulated or real engine failure.

Examination of the fuel system found that two of the fuel injectors in the right engine showed evidence of partial blockage by corrosion particles. Such blockage would have resulted in the over-fuelling of the other injectors and the engine running overly rich; reducing the maximum power available from that engine. There was, however, no evidence of a complete power loss, with both engines producing power at the time of impact.

The ATSB found that shortly after take-off, the flight instructor very likely conducted a simulated failure of the right engine in environmental conditions and a configuration in which the aircraft was unable to maintain altitude with one engine inoperative. Power was not immediately restored to the right engine to discontinue the exercise and the pilots were unable to maintain altitude or heading, particularly with the aircraft banked towards the inoperative engine. The pilots did not reduce power and land ahead, as required by the Airplane Flight Manual, resulting in a loss of directional control and roll. The loss of control occurred at a height too low to recover and the aircraft impacted terrain.

The instructor had limited experience in multi-engine aeroplanes with retractable landing gear and only one short flight in the Angel 44 aircraft several years earlier. Therefore, the instructor was likely unfamiliar with the time necessary for the landing gear and flaps to retract (significantly longer than other aircraft the instructor had flown) and the associated detrimental effect that extended flaps and landing gear had on the aircraft’s single-engine climb performance. This likely influenced the decision to initiate a low-level simulated engine failure and diminished the instructor’s ability to interpret and manage the situation.

Additionally, the pilot (in the left seat) had not flown for 3 years prior to the accident flight, which likely resulted in a decay of skills at managing tasks such as an engine failure after take-off. The pilot probably over-estimated their self-assessed competency for the planned task and did not demonstrate proficiency at a safe height before the low-level simulated engine failure.

The ATSB found that the right-side altimeter was probably set to an incorrect barometric pressure, resulting in it over-reading the aircraft’s altitude by about 90 ft.

The aircraft had not been flown regularly for more than 2 years and the engines had not been preserved in accordance with the manufacturer’s procedures. Both engines had mild internal corrosion and the right engine had signs of water contamination within the fuel system, including in the engine‑driven fuel pump and fuel injection servo. Corrosion particles in the fuel injection servo likely originated from the fuel tank. These particles lodged in two of the fuel injection nozzles and contributed to the right engine running overly rich, backfiring and a reduction in maximum power available.

Safety message

Flight reviews

Flight reviews that are conducted without the oversight of a training organisation remove the opportunity to include training. Due to the known limitations of self-assessed competency, pilots who choose this option should have recent demonstrated proficiency in all of the required exercises.

Simulated engine failures

In light twin-engine aeroplanes, loss of power on one engine shortly after take-off poses a high risk due to low altitude, low airspeed and generally limited single-engine climb performance. The asymmetric thrust can lead to a loss of directional control that, if mishandled, will likely result in an accident due to insufficient height above the ground to recover.

The regulatory requirement to use simulators for conducting engine failure after take-off exercises has eliminated the risk for those aircraft where simulators are available. However, where simulators are not available, there is still a requirement to perform the exercise in the aircraft. In those situations, it is essential to understand the risks and ensure effective controls are in place to prevent the simulation turning into a loss of control at low level, where recovery will probably not be possible. Consideration of these risks should include:

  • the method of simulating engine failure
  • instructor/check pilot training, experience and proficiency specific to the aircraft make and model
  • ensuring the pilot/student has first demonstrated the ability to maintain asymmetric control at a safe height and understands handling one engine inoperative flight and associated risks
  • thorough pre-flight briefing including minimum control speed, configuration including flaps and landing gear, safe intentional single-engine speed, one engine inoperative climb performance and limitations
  • ensuring the aircraft is in a configuration and at an airspeed at which climb with one engine inoperative is possible
  • criteria for aborting the procedure including airspeed, height above terrain/obstacles, directional control and bank angle
  • effect of, and time required to restore power to the simulated inoperative engine
  • understanding when a reduction in power and landing ahead may be ultimately necessary to avoid a loss of control.

Attempting to continue flight with one engine inoperative in a multi-engine aeroplane when directional control cannot be maintained, carries a high risk of an accident and fatal injuries.

Airframe and engine preservation

If an aircraft is not flown regularly, the airframe and engine/s should be preserved in accordance with the manufacturer’s procedures. Incorrect or inadequate preservation can increase the likelihood of in-flight failures, with the associated safety risks.

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  1. Eastern Standard Time (EST): Coordinated Universal Time (UTC) + 10 hours.
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The occurrence

Context

Safety analysis

Findings

Sources and submissions

Preliminary Report

Sequence of events

On 14 December 2019, two pilots were preparing to conduct a flight review[1] in an Angel Aircraft Corporation Model 44 aircraft, registered VH-IAZ (IAZ) (Figure 1). The aircraft was owned and operated by the pilot under review, who was to occupy the left seat. The right-seat pilot had a Grade 1 flight instructor rating. The flight was to be conducted as a private flight and the right-seat pilot was the pilot in command for the flight.

Figure 1: VH-IAZ (when formerly registered as VH-IOZ)

Figure 1: VH-IAZ (when formerly registered as VH-IOZ). Source: Provided to the ATSB

Source: Provided to the ATSB

Closed circuit television footage from Mareeba Airport, Queensland, showed the aircraft taxi and park outside a hangar at 0922 Eastern Standard Time.[2] A witness observed the left-seat pilot in the aircraft conducting engine run-ups between 0915 and 0930. The aircraft engines were then shut down.

At 1046, the pilots taxied the aircraft from outside the hangar towards the runway intersection. In recorded radio transmissions, the left-seat pilot broadcast on the common traffic advisory frequency that IAZ was taxiing for runway 28.[3]

At 1054, the left-seat pilot broadcast that IAZ was entering and backtracking the runway and 4 minutes later, that the aircraft had commenced the take-off roll on runway 28. Witnesses heard the aircraft during the take-off roll and reported that it sounded like one of the engines was hesitating and misfiring. An aircraft maintainer at the airport observed the aircraft take off and reported seeing black sooty smoke trailing from the right engine. He then watched the aircraft climb slowly and turn right towards the north. Another witness who heard the aircraft in flight reported that it sounded normal for that aircraft, which had a distinctive sound because the engine’s exhaust gases pass through the propellers.

Once airborne, the pilot broadcast that they were ‘making a low-level right-hand turn and then climbing up to not above 4,500 [feet] for the south-west training area.’

About 2 minutes later, the right-seat pilot broadcast that they were just to the west of the airfield in the training area at 2,500 ft and on climb to 4,000 ft, and communicated with the pilot of a helicopter operating in the area.

After 8 minutes in the training area, the left-seat pilot broadcast that they were inbound from the training area and 2 minutes later, that they were joining crosswind for runway 28. No further transmissions were heard from the aircraft.

Witnesses then saw the aircraft touch down on the runway and take off again, and heard one engine ‘splutter’ as the aircraft climbed to between 300 and 450 ft above ground level. At about 1115, the aircraft was observed overhead a banana plantation beyond the end of the runway in a right descending turn, before it suddenly rolled right. Witnesses observed the right wing drop to near vertical and the aircraft collided with terrain in a cornfield. Both pilots were fatally injured and the aircraft was destroyed.

Weather and environmental information

At 1115 EST, the temperature was 34 ºC, the dewpoint 15 ºC, and the wind from 266º at 6 kt gusting to 9 kt. There was no cloud and the QNH[4] was 1012 hPa.

The aerodrome elevation was 1,650 ft and with the given temperature and QNH, the density altitude[5] was 4,440 ft.

Recorded data

The aircraft was not equipped with a flight data recorder or cockpit voice recorder, nor was it required to be. A witness reported watching the aircraft track on OzRunways,[6] but the ATSB has not yet obtained any recorded data for the flight.

Aircraft information

The Angel Aircraft Corporation Model 44 was an eight-seat, twin-engine aircraft with retractable tricycle landing gear. It was designed for short take-off and landing distances, long endurance and the ability to carry a heavy payload. The aircraft was powered by two Lycoming IO-540-M1C engines with Hartzell three-blade constant speed feathering[7] HC-E3YR-2ALTFC pusher propellers mounted aft of the engines.

IAZ was manufactured in the United States in 2008 with serial number 004. It was first registered in Australia in January 2010 as VH-IOZ, deregistered in November 2017 and reregistered as VH-IAZ in March 2019. The aircraft was approved to operate under the instrument flight rules[8] and in the charter category.

The factory-rebuilt right engine was installed in May 2017 and had run for a total of 2.2 hours before the accident flight. The factory-overhauled left engine was installed in June 2016 and had run for a total of 12.7 hours prior to the accident flight.

On 10 December 2019, two new spark plugs were fitted to cylinder No. 3 on the right engine and one spark plug was replaced on cylinder No. 1 on the left engine due to magneto drops during ground runs. The engines were subsequently ground run satisfactorily.

The last maintenance release[9] (MR) was issued on 30 April 2019 and the aircraft had 1,803.5 hours total time in service. No daily inspection or additional flight time was recorded on the MR.

Operational information

The pilot under review (left seat) had accrued over 20,000 flying hours, approximately 300 of which were in IAZ.

The right-seat pilot held an air transport pilot licence and had accrued approximately 5,000 hours of aeronautical experience. He had not previously flown IAZ.

Wreckage and impact information

Examination of the aircraft wreckage indicated that the aircraft impacted terrain right wingtip first, then nose, followed by the left wingtip. The aircraft then pivoted about the left wing and the fuselage came to rest upright (Figure 2).

Figure 2: Accident site

Accident site

Source: ATSB

Continuing investigation

The investigation is continuing and will include examination of the following:

  • recovered components including engines and propellers
  • the aircraft’s maintenance and operational records
  • aircraft and site survey data
  • pilot qualifications, experience and medical history
  • regulatory requirements for flight reviews
  • previous research and similar occurrences.

     

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The information contained in this preliminary report is released in accordance with section 25 of the Transport Safety Investigation Act 2003 and is derived from the initial investigation of the occurrence. Readers are cautioned that new evidence will become available as the investigation progresses that will enhance the ATSB's understanding of the accident as outlined in this report. As such, no analysis or findings are included in this report.

 

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  1. Flight reviews are required to ensure pilots continue to be competent in exercising the privileges of their licences and ratings.
  2. Eastern Standard Time (EST): Coordinated Universal Time (UTC) + 10 hours.
  3. Runway number: the number represents the magnetic heading of the runway. Runway 28 at Mareeba was on a magnetic heading of 283°.
  4. QNH: the altimeter barometric pressure subscale setting used to indicate the height above mean seal level.
  5. Density altitude is pressure altitude corrected for temperature. In layman's terms, it directly affects the performance parameters of any aircraft, and in effect it is the equivalent altitude of where, performance-wise, the aircraft ‘thinks’ it is. The higher the density altitude, the lower the aircraft performance, and vice versa. (Skybrary)
  6. OzRunways is an electronic flight bag application that provides navigation, weather, area briefings and other flight-planning information.
  7. Feathering: the rotation of propeller blades to an edge-on angle to the airflow to minimise aircraft drag following an in-flight engine failure or shutdown.
  8. Instrument flight rules (IFR): a set of regulations that permit the pilot to operate an aircraft to operate in instrument meteorological conditions (IMC), which have much lower weather minimums than visual flight rules (VFR). Procedures and training are significantly more complex as a pilot must demonstrate competency in IMC conditions while controlling the aircraft solely by reference to instruments. IFR-capable aircraft have greater equipment and maintenance requirements.
  9. Maintenance release: an official document, issued by an authorised person as described in Regulations, which is required to be carried on an aircraft as an ongoing record of its time in service (TIS) and airworthiness status. Subject to conditions, a maintenance release is valid for a set period, nominally 100 hours TIS or 12 months from issue.
General details
Date: 14 December 2019   Investigation status: Completed  
Time: 1115 EST   Investigation level: Defined - click for an explanation of investigation levels  
Location   (show map): near Mareeba Airport   Investigation phase: Final report: Dissemination  
State: Queensland   Occurrence type: Collision with terrain  
Release date: 21 October 2020   Occurrence category: Accident  
Report status: Final   Highest injury level: Fatal  

Aircraft details

Aircraft details
Aircraft manufacturer Angel Aircraft Corp.  
Aircraft model 44  
Aircraft registration VH-IAZ  
Serial number 004  
Operator Anju Azul Aviation  
Type of operation Private  
Sector Piston  
Damage to aircraft Destroyed  
Departure point Mareeba Airport, Queensland  
Destination Mareeba Airport, Queensland  
Last update 21 October 2020