[Peetwo]

ATSB release prelim reports for two fatal Cessna accidents -

Via the ATSB website:

Preliminary report
Published: 8 December 2017

On 28 October 2017, a Cessna Aircraft Company T310R, registered VH-JMW, was being operated on a private flight from Toowoomba, Queensland to The Lakes aerodrome, New South Wales. The aircraft had been flown from The Lakes to Toowoomba earlier that day.

The aircraft departed Toowoomba at 1434 Eastern Daylight-saving Time (EDT)[1]. The pilot was the owner of the aircraft and there was a passenger in the other front seat.

During the flight, transponders in the aircraft provided flight information indicating that the aircraft flew at 9,500 ft in the cruise. Weather forecasts and observations indicated good weather conditions throughout the flight, with a light easterly wind in the vicinity of the destination.

About half a nautical mile north of The Lakes aerodrome, witnesses driving south on the Pacific Highway observed the aircraft flying just to the west of the highway at low altitude in a southerly direction. The landing gear was extended and the aircraft was descending slowly. The aircraft was then observed to roll left and descend rapidly.

The aircraft collided with terrain at approximately 1555, in a narrow wooded strip of land east of the Pacific Highway, between the highway and the main northern railway line. The accident was 800 m from The Lakes runway 16 threshold, in line with the runway direction (Figure 1). The pilot and passenger were fatally injured.

Figure 1: Flight path approaching The Lakes. Radar data was lost below 900 ft altitude


Source: Google Earth modified by ATSB

Aircraft information
VH-JMW was a Cessna T310R, six seat, twin-engine aircraft, powered by two Teledyne Continental Motors TSIO-520-NB turbocharged engines (Figure 2). It had six fuel tanks, comprising the main fuel tanks in the wingtip pods, and two auxiliary fuel tanks in each wing.

Figure 2: Cessna T310R VH-JMW

Source: flightaware.com

Wreckage examination
On-site examination of the wreckage, surrounding markings on trees and the ground indicated that the aircraft impacted terrain in a steep nose-down attitude and banked to the left. The aircraft was in a landing configuration.

The left wing had separated outboard of the left engine, and both the wing-tip pods had separated from the wings. The remaining fuel tanks were also breached and no fuel was found, however a smell of aviation fuel was noted by emergency responders at the accident site. There was no evidence of fire.

Examination of the engines and propellers indicated that the left engine was producing no power and the right engine was likely producing low power at the time of the accident.

A number of aircraft components, instruments and electronic devices were recovered from the accident site by the ATSB for further examination.

The aircraft was not equipped with a flight data recorder or a cockpit voice recorder, nor was it required to be.

Ongoing investigation
The investigation is continuing and will include consideration of the:

• pilot’s qualifications, experience and medical information
  
• fuel planning for the flight
  
• component examination
  
• witness information
  
• weather information
  
• recovered instruments and available electronic data.
  

 
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&..

Preliminary report
Published: 7 December 2017

Sequence of events
On 23 October 2017, two pilots from Air Frontier were operating a Cessna C210L aircraft, registered VH-HWY (HWY), on a charter flight from Darwin Airport to Elcho Island, Northern Territory. The pilot in the left seat was the pilot in command, under supervision of the right seat pilot and the flight was operating under the visual flight rules (VFR).[1]

The pilots had submitted a flight plan to track via ‘VFR route No. 2’ to Castle Point (Figure 1) and then direct to Elcho Island.

Figure 1: Darwin Airport and pertinent features on the visual terminal chart


Source: Airservices annotated by ATSB

The aircraft took off from runway 29 at about 1307 Central Standard Time.[2] Recorded air traffic control (ATC) data showed that as the aircraft climbed through 700 ft, the pilot[3] contacted ATC and was cleared to climb to 7,500 ft and turn onto a heading of 320° (items 1 and 2 in Figure 2). About 5 minutes later, the controller cleared the aircraft to turn right onto a heading of 100° (item 3 in Figure 2).

As the aircraft tracked east and passed through 6,100 ft on climb, the pilot requested clearance to divert 5 miles left or right of track due to weather (item 4 in Figure 2) and to climb to 9,500 ft. Air traffic control advised that left of track was unavailable due to the nearby active restricted airspace (Figure 1) and so was cleared to divert up to 5 NM right of track and to climb to 9,500 ft. Just over 2 minutes later, the controller cleared the aircraft to operate up to 10 NM right of track (item 6 on Figure 2).

At 1325, the aircraft turned north-east and continued to climb for another 4 minutes, to about 10,000 ft. At 1329, the controller recalled seeing the aircraft turn abruptly to the south west. The controller asked the pilot if they required alternate tracking (item 8 on Figure 2). The pilot replied ‘affirm’ and the controller cleared the aircraft to deviate up to 20 NM right of route. The aircraft continued to track south west.

Figure 2: Aircraft track with pertinent broadcasts from the aircraft and air traffic control


Source: RAAF radar data overlaid on Google earth, annotated by ATSB

At 1332, the aircraft’s recorded groundspeed increased from 130 kt to 150 kt. Air traffic control radar recorded the aircraft descending and climbing between 9,600 ft and 10,100 ft (see the section titled Recorded data). At 1332:20 while at 10,100 ft and a recorded groundspeed of 100 kt, the aircraft’s altitude (radar mode ‘C’) disappeared from the radar display (item 9 in Figure 2). The controllers immediately assessed the absence of this line as abnormal.

About 10 seconds later, three short transmissions were recorded, resulting from separate ‘push-to-talk’ activations, likely from the aircraft’s radio. At 1332:45, the aircraft’s altitude (mode C) briefly reappeared, recording the aircraft at 5,100 ft and 70 kt groundspeed, and 15 seconds later the controllers reported that the aircraft disappeared from the radar screen. The controllers attempted to make radio contact with the pilot, but were unsuccessful.

Witnesses in the vicinity of Howard Springs (Figure 1) saw the aircraft descend rapidly in a relatively flat attitude with a portion of each wing missing. The main fuselage was found less than 1 NM from the last recorded radar position and both aircraft wings were located about 700 m south-east of that site.

Both pilots were fatally injured and the aircraft was destroyed.

Weather and environmental information
On the day of the occurrence, the environment was typical of the Northern Territory early wet season or ‘build‑up’, with unstable conditions, and showers and storms expected.

A thunderstorm to the north of Darwin, combined with the north-west sea breeze, triggered a convective cell to develop rapidly between 1300 and 1330 between Howard Springs and Koolpinyah (19 km to the north east). Based on the cloud top temperature, the top of the cell was around 6,000–7,000 ft at 1300, 9,000 ft at 1320, 13,000–14,000 ft at 1330, and around 14,000 ft at 1340. The developing cumulus clouds may have produced strong updrafts or downdrafts.

The air traffic controller and supervisor reported that their observations of the weather radar, using the Bureau of Meteorology internet website, indicated a cell (painted yellow, indicating rain) but not one that was indicative of a thunderstorm.

Witnesses reported seeing a large cumulus cell form over the Howard Springs area, which they described as a regular occurrence in the build-up season in Darwin. Some reported that the cloud went ‘very black’ at the time of the accident, and that starting about 10 minutes after the accident, it rained heavily for about an hour.

Recorded data
The aircraft was not equipped with a flight data recorder or cockpit voice recorder, nor was it required to be.

The aircraft’s altitude and groundspeed were recorded by the Darwin ATC radar for the last 6 minutes of the flight (Figure 3).

The aircraft’s airspeed was not recorded. The forecast wind at 10,000 ft was 10 kt from 190°, so the aircraft’s airspeed may have been up to 10 kt higher than the recorded groundspeed in the last few minutes of the flight. However, the actual airspeed cannot be accurately determined, given the likelihood of wind shear and turbulence in the air mass.

Manoeuvring speed
The manoeuvring speed was specified by the aircraft’s manufacturer as 118 kt at the aircraft’s maximum take-off weight, shown as a dotted line in Figure 3. At airspeeds above the manoeuvring speed, control inputs or turbulence may produce wing loading that can damage the aircraft’s structure. At airspeeds above about 145 kt, this loading can result in failure of the aircraft structure.

The graph shows that shortly after the aircraft climbed to 10,000 ft, the aircraft’s groundspeed exceeded the manoeuvring speed. The groundspeed remained above the manoeuvring speed, increasing to a maximum of 150 kt in the final minute of the flight.
During the same timeframe, the aircraft’s recorded altitude varied between 9,700 ft and 10,000 ft, above the cleared altitude of 9,500 ft.

Figure 3: VH-HWY recorded altitude and groundspeed for the last 6 minutes of flight


Source: RAAF radar data analysed by ATSB

Aircraft information
The Cessna Aircraft Company 210L is a six-seat, high cantilever wing, single-engine aircraft equipped with retractable tricycle landing gear and was designed for general utility purposes. The aircraft was powered by a Teledyne Continental IO-550P engine.
HWY was manufactured in the United States in 1974 and was first registered in Australia in 1988. The aircraft was operated in the charter category.

In 2012 the Federal Aviation Administration (FAA) published Airworthiness Directive (AD) 2012‑10-04 Wing main spar lower cap inspection. This AD was applicable to HWY and required an inspection of the left and right wing lower main spar caps for cracks. Aircraft technical documentation identified this AD was completed in June 2012 with no defects found. During scheduled maintenance completed in March 2016, the wing main spar carry through was replaced with a serviceable item due to corrosion. HWY was then operated by Air Frontier and maintained under an approved system of maintenance from March 2017.

A periodic inspection of the aircraft was completed on 26 September 2017 and a new maintenance release was issued, which was still current at the time of the occurrence. In addition, a scheduled 50 hourly inspection was completed on 23 October 2017. The maintenance release was current at the time of the occurrence and it was reported there were no concerns with aircraft serviceability prior to departure from Darwin Airport. In addition, the pilots did not advise ATC of any aircraft-related issues.

Wreckage and impact information
Examination of the aircraft wreckage indicated that the aircraft impacted terrain from a vertical descent, right side slightly down, in an almost level attitude. The wings were located about 24 m apart and about 740 m south-southeast of the fuselage, consistent with an in-flight breakup (Figure 4). There was no evidence of fire. Various aircraft components were located between the fuselage and an area about 70 m beyond the wings, over 810 m in total.

Figure 4: Google Earth images showing accident site and location of fuselage and wings


Source: Google Earth, modified by ATSB

Both wings had separated between 0.5 and 1.5 m outboard from the wing-to-fuselage attachment. The wing spars had fractured in over-stress, and exhibited bending deformation consistent with forces acting upwards and rearwards on the wings. Examination of the wings showed no evidence of pre-existing defects.

On-site examination of the severely impact-damaged fuselage (Figure 5), engine and propeller did not identify any pre‑existing faults or anomalies with the aircraft that could have contributed to the accident. However, a number of aircraft components were retained for further examination and testing. The propeller did not exhibit any evidence of rotation at impact, consistent with fuel exhaustion resulting from the ruptured integral wing-fuel tanks.

Figure 5: The fuselage, left and right wings


Source: Northern Territory Police and ATSB, modified by ATSB

Both pilots were secured in their seats prior to impact. Notwithstanding the severe disruption to the airframe, examination identified both pilot seats were about mid-travel with one locator pin on each seat still engaged in the seat rails.

Related occurrences
ATSB investigation AO-2011-160 involved a Cessna 210M aircraft, VH-WBZ, which broke up in flight. Although the precise circumstances were not known, a combination of aircraft airspeed with turbulence and/or control inputs generated stresses that exceeded the design limits of the aircraft structure.

The United States National Transportation Safety Board investigated seven in-flight breakups of Cessna 210 aircraft since 2000. All those occurrences involved flight into thunderstorms or associated turbulence, a loss of control following inadvertent flight into instrument meteorological conditions or a combination of both.

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

• recovered components and available electronic data
  
• aircraft and site survey data collected
  
• further interviews with a number of witnesses and involved parties
  
• weather conditions and its effect on the flight
  
• pilot qualifications and experience
  
• the aircraft’s maintenance and operational records
  
• the operator’s training and professional development programs
  
• previous research and similar occurrences.
  

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MTF...P2