AIRCRAFT ACCIDENT REPORT AND EXECUTIVE SUMMARY

Transcription

1 Section/division Accident and Incident Investigation Division Form Number: CA 12-12a AIRCRAFT ACCIDENT REPORT AND EXECUTIVE SUMMARY Reference: CA18/2/3/9445 Aircraft registration ZS-HCH Date of accident 30 May 2015 Time of accident 0540Z Type of aircraft Robinson R44 Raven II Type of operation Private (Part 91) Pilot-in-command licence type Private Age 58 Licence valid Yes Pilot-in-command flying experience Last point of departure Next point of intended landing Total flying hours Hours on type Vryburg, North West Province Wonderboom Aerodrome (FAWB), Gauteng Province Location of the accident site with reference to easily defined geographical points (GPS readings if possible) Open field next to the Delareyville Golf Course (GPS coordinates: South East) elevation 4440ft Meteorological Surface wind; Calm, Temperature; 8 C, Dew point; -3 C, Visibility; + 10km information Number of people on No. of people injured 2 No. of people killed 1 board Synopsis The pilot, accompanied by his youngest son, flew from their farm near Tosca to Vryburg where they landed. The pilot s wife then joined them for a private flight to Wonderboom aerodrome (FAWB). The pilot s wife was occupying the left front seat and the son was seated behind her. Shortly after take-off, the pilot s wife was having difficulty communicating with them via the headset she was wearing and requested the pilot to land somewhere in order for her to get another headset out from underneath her seat. The pilot s door was also not properly latched at the top and it was required to be opened and closed again in order to be latched properly. During an approach for landing the helicopter collided with a large tree, whereupon the pilot lost control and it impacted with the ground in a steep nose down attitude. The pilot succumbed to his injuries at the scene. His wife was seriously injured and was flown by air ambulance to Grand Central aerodrome (FAGC) and was transported from there by road ambulance to a private hospital in Johannesburg where she underwent surgery. The son suffered a bleeding nose and concussion. The helicopter was destroyed during the impact sequence. The investigation determined that during the descent the helicopter collided with a large blue gum tree, the pilot lost control and the helicopter impacted with terrain approximately 20m beyond the tree. Probable cause The helicopter collided with a tree while on the descent for an intended landing whereupon the pilot lost control of the helicopter before impacting with terrain. SRP date 8 August 2017 Release date 11 August 2017 CA 12-12a 07 FEBRUARY 2017 Page 1 of 33

2 Section/division Accident and Incident Investigation Division Form Number: CA 12-12a AIRCRAFT ACCIDENT REPORT Name of Owner : Chata Ranch Family Trust Name of Operator : Private (Part 91) Manufacturer Model Nationality Registration markings Place Date : 30 May 2015 Time : Robinson Helicopter Company : R44 Raven II : South African : ZS-HCH : Delareyville : 0540Z All times given in this report are Co-ordinated Universal Time (UTC) and will be denoted by (Z). South African Standard Time is UTC plus 2 hours. Purpose of the Investigation: In terms of Regulation of the Civil Aviation Regulations (2011) this report was compiled in the interest of the promotion of aviation safety and the reduction of the risk of aviation accidents or incidents and not to establish blame or liability. Disclaimer: This report is produced without prejudice to the rights of the CAA, which are reserved. 1. FACTUAL INFORMATION 1.1 History of flight On Friday, 29 May 2015, at approximately 0617Z the pilot took-off from his farm near Tosca in the North West Province and flew to Wonderboom Aerodrome (FAWB) in Pretoria where he landed at 0922Z. After the helicopter was refuelled, he took-off at 0959Z and flew back to his farm where he landed at 1223Z The next morning the pilot, accompanied by his youngest son, took-off from the farm at 0426Z and flew to the town of Vryburg where he landed to pick up his wife. After landing the son relocated to the left aft seat and the pilot s wife occupied the left front seat. According to the track data file that was downloaded from the global positioning unit (GPS),) which was recovered from the accident site, they departed CA 12-12a 07 FEBRUARY 2017 Page 2 of 33

3 from Vryburg at 0509Z flying in an easterly-north-easterly direction towards FAWB (see Figure 1). The official sunrise time on the day for Pretoria was 0445Z The GPS track data files were downloaded and the helicopter was observed to be on the approach for runway 04 at the Delareyville aerodrome (FADL). From the data gathered it was evident that the pilot commenced with the descent some distance out and at 0.55 nautical miles (1 kilometre) from the threshold of runway 04 the helicopter collided with a large blue gum tree next to the roadway (R507, public road between Ottosdal and Delareyville). Following impact with the tree he lost control and the helicopter impacted with the ground in a steep nose down attitude and came to rest on its right-hand side approximately 80 metres (m) beyond the tree in an open field. The cockpit/cabin structure was severely disrupted, the skid gear broke off and the tail boom was severed by the main rotor blades, which remained attached to the main rotor head assembly The pilot, who was occupying the right front seat, succumbed to his injuries at the accident scene. The pilot's wife sustained serious injuries to her lower back, neck, ribs and left ankle, while she was still secured to her seat by the safety belt inside the wreckage. Her son, who was seated behind her, braced himself prior to impact and suffered from a bleeding nose and concussion. Following initial medical observations on site, the pilot's wife was transported by air mercy flight from Delareyville to Grand Central aerodrome (FAGC) from where she was taken by road ambulance to a private hospital in Johannesburg. She was admitted to the intensive care unit (ICU) and underwent surgery to her back and left ankle. The son was admitted to the same hospital where he was kept overnight for observation, he was discharged the following day with concussion. Neither of the two surviving occupants could recall seeing the tree prior to the helicopter colliding with it The pilot s wife was interviewed while she was in hospital in Johannesburg. According to her she was having problems with her noise reducing headset and was unable to communicate properly with her husband and son during the flight. She requested her husband to land en route in order for her to get another headset out from underneath her seat as they had additional headsets on board. She further indicated that they had two different brands of headsets on board and was going to change from the one brand to another. These two different headset brands were observed on the scene. She further mentioned that the pilot s door was not properly latched at the top, which resulted in unnecessary noise, something he would have attended to after they had landed. CA 12-12a 07 FEBRUARY 2017 Page 3 of 33

4 1.1.6 The accident occurred during daylight conditions at a geographical position that was determined to be South East at an elevation of 4440 feet above mean sea level (AMSL). Route flown prior to the accident Figure 1: Google earth overlay of route flown from Vryburg to Delareyville Threshold Runway 04, Delareyville aerodrome Accident site Route flown by ZS-HCH prior to impact Figure 2: Google earth overlay illustrate the flight path of the helicopter in relation to the runway 1.2 Injuries to persons CA 12-12a 07 FEBRUARY 2017 Page 4 of 33

5 Injuries Pilot Crew Pass. Other Fatal Serious Minor None Damage to aircraft The helicopter was destroyed during the impact sequence. Figure 3: The main wreckage as it came to rest 1.4 Other damage Apart from minor damage to vegetation no other damage was caused. 1.5 Personnel information Pilot-in-command (PIC) CA 12-12a 07 FEBRUARY 2017 Page 5 of 33

6 Nationality South African Gender Male Age 58 Licence number Licence type Private pilot Licence valid Yes Type endorsed Yes Ratings None Medical expiry date 31 December 2015 Restrictions Must wear corrective lenses Wheels up landing runway 17 at Grand Central aerodrome in a Cessna T210L, ZS-PNG, 21 May Previous accidents/ Collided with wires during low level flying in Robinson serious incidents R44, ZS-HCH on 20 May Collided with wires during low level flying in Robinson R44, ZS-HCH on 22 August (i) The pilot started flying aeroplanes in 1986 and was issued with a private pilot licence. He then allowed his pilot licence to lapse for a period of thirteen years and renewed his licence (aeroplane) again on 26 April 2001 after having redone his training. (ii) The pilot was the holder of a private pilot licence on helicopters as well as aeroplanes. He kept both pilot licences valid and owned an aeroplane and the helicopter at the time of the accident. (iii) According to available information (CAA pilot file) his first training flight on helicopters was on 7 September 2010 and he completed his training on 22 March The required paperwork was submitted the next day to the regulating authority and he was issued with a private pilot licence (helicopter). His last flight skills test (helicopter) was conducted on 1 July It was further noted that all his helicopter flying hours entered in his logbook was conducted on the helicopter in question (ZS-HCH), including his flying training. A copy of the pilot s helicopter flying logbook was made available in electronic format to the investigator. The last entry in his logbook was also dated 1 July 2014 with his helicopter flying hours reflected at the time to be (iv) The flight folio that was recovered from the accident site had only three entries on page 1 (new book) and portrayed the period 16 to 24 May 2015 where five hours were flown. The GPS information that was downloaded CA 12-12a 07 FEBRUARY 2017 Page 6 of 33

7 along with the Hobbs meter reading of the helicopter provided additional information such that it could be ascertained that the pilot flew several hours the previous day. The combined flying hours for the flights on 29 and 30 May 2015 were 6.1 flying hours. The helicopter flying hours in the table below were obtained from the pilot logbook, the helicopter flight folio as well as the Hobbs meter and GPS data. NOTE: There was a ten month period where no documented evidence was available on the pilot s helicopter flying hours. Flying experience (helicopter) Total hours Total past 90-days 11.1 Total on type past 90-days unknown Total on type Flying experience (aeroplane) Total hours Total past 90-days 35.5 Copies of the pilot s aeroplane flying logbook were obtained, the last entry in his logbook was dated 8 March The total flying hours accumulated on the date was Copies of his aircraft (Cessna 206, ZS-DJB) flight folio were also obtained, which reflect the hours flown over the period 17 September 2014 until 28 May It was noted that from 8 March 2015 until 28 May 2015 the pilot had flown a further 35.5 hours with the aircraft, which brings his total aeroplane flying hours to Total flying experience (aeroplane and helicopter) Total hours on aeroplane Total hours on helicopter Grand total Aircraft information Airframe: CA 12-12a 07 FEBRUARY 2017 Page 7 of 33

8 Type Robinson R44 Raven II Serial number Manufacturer Robinson Helicopter Company Year of manufacture 2008 Total airframe hours (at time of accident) Last MPI (hours & date) October 2014 Hours since last MPI 85.3 C of A (Issue date) 21 August 2008 C of A (Expiry date) 20 August 2015 C of R (Issue date) (present owner) 20 April 2011 Operating categories Standard Part 91 Record of The helicopter was involved in two previous occurrences; previous Collided with wires during low level flying on 20 May damage to Collided with wires during low level flying on 22 August the helicopter According to the airframe logbook, page 89, the helicopter was involved in a main rotor blade wire strike incident that occurred on 20 May 2011 at airframe hours. New main rotor blades and tail rotor assembly were installed following the occurrence. According to the airframe logbook, page 91, the helicopter was involved in another main rotor blade wire strike incident on 22 August 2012 at airframe hours. New main rotor blades were installed following the occurrence. The flight folio was retrieved from the accident site. It was a new book with only three entries on page 1. The first entry was dated 16 May 2015, followed by a second entry on the same day and then an entry on 24 May The flight on 29 May 2015 from the pilot s farm near Tosca to FAWB and back to the farm was not entered in the flight folio, nor was there any record with regard to fuel uplifts with 11.1 hours flown over this period. Engine: Type Lycoming IO-540-AE1A5 Serial number L E CA 12-12a 07 FEBRUARY 2017 Page 8 of 33

9 Hours since new Hours since overhaul T.B.O. not yet reached Main rotor blades: Type Robinson C016-7 Serial numbers 2450, 2463 Hours since new Hours since overhaul T.B.O. not yet reached 1.7 Meteorological information An official weather report was obtained from the South African Weather Services (SAWS). The closest SAWS Automatic Weather Station where data was recorded to the accident scene was at Ottosdal, which was 55 km south-east of Delareyville. Parameter 0500Z 0600Z Wind Calm Calm Temperature 3 C 8 C Humidity 57% 45% Dew-point - 5 C - 3 C Pressure 1024 HPa 1024 HPa 1.8 Aids to navigation The helicopter was equipped with standard navigational equipment. Also on board was a Garmin aera 500 GPS portable unit that was recovered from the accident site. 1.9 Communication The helicopter was equipped with a standard communication device. The pilot was flying outside of controlled airspace underneath the terminal control area (TMA) when the accident occurred. CA 12-12a 07 FEBRUARY 2017 Page 9 of 33

10 1.10 Aerodrome information Aerodrome location Delareyville (FADL) Aerodrome co-ordinates South East Aerodrome elevation 4495 feet above mean sea level Runway designations 04/22 Runway dimension 1200m x 45m Runway used Not applicable Runway surface Gravel Approach facilities None Aerodrome status Licensed The helicopter crashed onto an open grass field 0.55 nm (1 kilometre) short of the threshold of runway 04 at FADL Flight recorders The helicopter was not equipped with a flight data recorder (FDR) or a cockpit voice recorder (CVR), nor was it required by the regulations to be fitted to this type of helicopter Wreckage and impact information The helicopter collided with a large blue gum tree on the eastern side of the R507 roadway when driving in a northerly direction from Ottosdal towards the town of Delareyville. The helicopter was flying in a north-easterly direction when the accident occurred. It impacted with the ground to the left of the tree shortly after making contact with the tree in a steep nose down attitude. The main wreckage skidded for a distance of 80m before coming to rest on its right-hand side. The tail boom was severed twice by the main rotor blades and the boom structure came to rest approximately 80m from the main wreckage. The aft tail boom structure, which supported the tail rotor assembly, as well as the vertical and horizontal stabilizer, was found 30m from the main wreckage. The stinger was observed to be bent upwards and the lower vertical stabilizer displayed evidence of deformation associated with ground contact. The tail rotor gearbox and head assembly CA 12-12a 07 FEBRUARY 2017 Page 10 of 33

11 remained secured to the aft tail boom structure, the two tail rotor blades fractured near the blade hub. A section of the tail rotor drive shaft was still secured to the input housing of the tail rotor gearbox and a section of the tail rotor drive shaft was still secured to the main rotor gearbox output housing. A section of the tail rotor drive shaft, approximately 2m in length, was located some distance from the main wreckage. The main rotor drive train was substantially damaged during the impact sequence. The four drive belts were found to be intact. Although the cockpit structure was severely disrupted flight control continuity could be established and all failures were associated with overload mode. The engine that was still contained with the airframe was removed and subjected to a teardown inspection. The tree that the helicopter collided with Tail boom Main wreckage The aft tail section Figure 4: An aerial view of the accident site (photograph courtesy of the SA Police Services) CA 12-12a 07 FEBRUARY 2017 Page 11 of 33

12 The main wreckage The tree which the helicopter collided with The R507 roadway Figure 5: Shows the main wreckage and the tree that the helicopter collided with, Figure 6: The arrows indicate tree branches that were severed by the main rotor blades CA 12-12a 07 FEBRUARY 2017 Page 12 of 33

13 Figure 7: Two of the tree branches that were severed Figure 8: A close view of one of the tree branches that was severed CA 12-12a 07 FEBRUARY 2017 Page 13 of 33

14 Figure 9: A view of the main wreckage Figure 10: The main wreckage lower fuselage with the skid gear ripped out A red 10 litre container that was filled with Avgas was located at the accident site. CA 12-12a 07 FEBRUARY 2017 Page 14 of 33

15 The container remained intact. It could not be determined where this container was placed on board the helicopter during the flight. The main fuel tank was ruptured during the impact sequence. The auxiliary tank remained intact and was found to be filled to capacity as can be seen in Figure 11. The photograph was taken after the main wreckage was placed in an upright position. Figure 11: Auxiliary fuel tank was filled to capacity (wreckage was placed in up-right position) CA 12-12a 07 FEBRUARY 2017 Page 15 of 33

16 Figure 12: The aft tail rotor assembly, vertical fin with a section of the tail rotor drive shaft Figure 13: A section of the tail boom structure as found on the scene The destruction to the cockpit/ cabin area can be viewed in Figure 14 below. The CA 12-12a 07 FEBRUARY 2017 Page 16 of 33

17 destruction to the right side (looking at the wreckage from behind) can be seen to be more extensive in relation to the left side. The pilot's three point safety harness was found to still be latched in position. The red 10L Avgas container that was recovered on the scene can also be seen. Figure 14: A view of the main wreckage after it was turned upright 1.13 Medical and pathological information According to the medico-legal post mortem report the pilot s cause of death was due to; The base of the skull that fractured with primary brain injuries Fire There was no evidence of a pre- or post-impact fire Survival aspects Two of the three occupants on board the helicopter survived the accident. The pilot was trapped underneath the wreckage as it came to rest on its right-hand side. He CA 12-12a 07 FEBRUARY 2017 Page 17 of 33

18 succumbed to his injuries on the scene The pilot's wife who was occupying the left front seat suffered severe spinal injury, she also injured her neck and fractured her left ankle. She was properly secured by making use of the helicopter equipped three point safety harness. Even though the cabin structure was severely disrupted, where she was seated, the seat structure remained secured to the floor structure. She was flown by air ambulance to Grand Central aerodrome (FAGC) from where she was transferred by road ambulance to a private hospital in Johannesburg where she underwent surgery. Medical facilities in the area of the accident were not conducive to such specialised procedures The son, who was seated behind his mother, suffered concussion and a bleeding nose. He was attended to at the scene by medical personnel and was admitted to the same hospital as his mother for observation purposes. He was discharged the next day. He was properly secured by making use of the helicopter equipped safety harness. The seat and associated structure where he was seated remained intact during the impact sequence Tests and research The engine, a Lycoming IO-540-AE1A5, serial number, L E was removed from the wreckage after the helicopter was recovered. Due to impact damage it was not possible to subject the engine to a bench test procedure and a teardown inspection was conducted on Monday, 6 July Both magnetos were removed from the engine and subjected to a bench test at an approved maintenance facility. Both magnetos provided spark associated with normal operation. The left-hand magneto was found to be noisier than the right-hand one, and during a partial dismantle procedure the shaft bearing was found to display some evidence of wear. An engine teardown report can be found attached to this report as Annexure A Garmin aera 500 GPS CA 12-12a 07 FEBRUARY 2017 Page 18 of 33

19 Figure 15: This GPS unit was found on the accident scene A Garmin aera 500 GPS was retrieved from the accident site, the unit was intact and it was possible to download several flight tracks from it. The track that the pilot flew from his farm near Tosca to FAWB and back, the day prior to the accident flight, could be viewed as well as the accident flight until the point of impact. Observing the track flown on the morning of 30 May 2015 from Vryburg it was noted that the pilot deviated en route to Delareyville as the direct track to FAWB would have taken them to the north of the town. He commenced with a slight right turn and flew in a north-easterly direction with his flight path taking them to the south of the town where the accident occurred in an open field near the Delareyville golf course. CA 12-12a 07 FEBRUARY 2017 Page 19 of 33

20 Runway 04 The approach path that was flown Figure 16: Google Earth overlay displaying the approach path that was flown Approach path Figure 17: Google Earth overlay displaying the approach path from a different angle 1.17 Organizational and management information This was a private flight; the pilot was also the owner of the helicopter. CA 12-12a 07 FEBRUARY 2017 Page 20 of 33

21 The aircraft maintenance organisation that carried out the last maintenance inspection on the helicopter prior to the accident flight was in possession of a valid AMO approval certificate Additional information None Useful or effective investigation techniques No new methods were applied. 2. ANALYSIS 2.1 Man (Pilot) The pilot was the holder of a valid private pilot licence on helicopters as well as aeroplanes. He flew several hours with the helicopter the previous day and there was no defects entered in the flight folio that was recovered from the accident site. From the flight track data as depicted in Figure 1, page 4 of this report, it was noted that the pilot changed his route after passing the halfway point between Vryburg and Delareyville. The flight continued normally and was tracking towards the south of the town of Delareyville. At no stage during the flight was there an unusual or sudden change in the flight profile of the helicopter, which was observed to be on final approach for runway 04 at FADL. It was a known fact that the pilot was going to land en route to FAWB and he most probably opted to do so at FADL, which was a safe option as it was a licensed aerodrome. Flying a helicopter allows a pilot with many landing options should the environment be conducive to such a landing as there could be a risk involved, i.e., a pilot should avoid landing in tall grass as the exhaust system can set the veld alight, there could also be wires that blend in with the environment or uneven/rocky terrain that can damage the helicopter. This was not the first time the pilot had collided with an object aloft while flying this helicopter. According to available evidence he was involved in two previous CA 12-12a 07 FEBRUARY 2017 Page 21 of 33

22 occurrences where he had collided with wires. Both these occurrences are referred to in subheading 1.5 on page 6 of this report. According to the two passengers that survived the accident neither of them could recall seeing the tree prior to contact with it. The possibility that the pilot saw the tree when he was in close proximity to it could not be ruled out. The tree branches that were severed by the blades display a substantial angle; this was supported by the helicopter impacting the ground to the left of the tree. The cutting angle was in excess of 30, which indicates a steep bank angle to the left, however with this amount of bank he was unable to avoid making contact with the tree, which resulted in a loss of control. 2.2 Machine (helicopter) The helicopter was maintained in accordance with the approved maintenance schedule and no reported defects were found entered in the flight folio that was recovered from the scene. The auxiliary fuel tank was found to be filled with fuel, the main fuel tank was however, ruptured. The day prior to the accident flight the pilot flew from his farm near Tosca to FAWB and back, which was a flight of several hours without any defect being recorded. The AMO that maintained the helicopter was also located at FAWB, so should there have been any defects the opportunity was there to attend to the problem. No defect(s) were reported to the AMO on the day. Analysing the data that was downloaded from the GPS unit it was noted that the pilot commenced with a gradual descent flying toward the threshold of runway 04 at FADL. At no time prior to making contact with the tree was there any sudden deviation from the flight path that could have been associated with an emergency or an unusual situation on board the helicopter. The engine was subjected to a teardown inspection and no mechanical evidence could be found that the engine was not functioning satisfactorily at the time of impact Environment CA 12-12a 07 FEBRUARY 2017 Page 22 of 33

23 The prevailing weather conditions at the time had no influence on the accident. There were no clouds and visibility was more than 10km. The terrain between Vryburg and Delareyville was flat and there was ample space available for an unscheduled or forced landing should that have been required. 2.4 Crash survivability The pilot incurred severe head trauma during the impact sequence, he was not wearing a flying helmet. Flying with an approved flying helmet could have provided him with the necessary protection to such a degree that his chances of surviving the accident could have been much better. The two occupants that were seated on the left side of the helicopter survived the accident. The injuries sustained by the front seated passenger were due to the destruction of the front as well as the lower fuselage structure, which was manufactured from glass fibre. The pilot's wife or left front seat passenger remained secured to her seat via the helicopter equipped three points safety harness. 2.5 Conclusion The flight was nothing out of the norm for the pilot as he had flown several hours the previous day with the same helicopter to the same destination, that being FAWB. The flight folio that was recovered on the scene did not reflect any entry that could have been associated with a defect on the helicopter prior to the flight. It was noted that the pilot deviated from the intended flight route while flying from Vryburg to FAWB by turning right approximately halfway between Vryburg and Delareyville and was observed flying to the south of the town of Delareyville. The direct route to FAWB would have taken them to the north of the town. It could be seen from the GPS data that the pilot was flying towards FADL as the helicopter was on approach (lined up) for runway 04 when the accident occurred. The deviation came about due to the pilot s door not being properly latched at the top and the left front seat passenger experiencing problems communicating with them via the headset she was wearing and wanted to change it for another headset, which was underneath her seat. It would appear that the pilot s attention became distracted during a critical phase of the flight and he most probably saw the tree seconds before colliding with it head on. He banked left in an attempt to avoid colliding with the tree but the blades and possibly some of the fuselage made contact with the tree and control was lost and the helicopter impacted with the CA 12-12a 07 FEBRUARY 2017 Page 23 of 33

24 ground. 3. CONCLUSION 3.1 Findings The pilot was the holder of a valid private pilot licence on helicopters as well as aeroplanes. He had the helicopter type endorsed on his licence The pilot was the holder of a valid aviation medical certificate that was issued by a designated medical examiner. He had to wear corrective lenses while flying The pilot had flown the day prior to the accident flight from his farm near Tosca to FAWB and back to his farm with the same helicopter without any defect being recorded in the flight folio On the day of the accident he flew from his farm accompanied by his youngest son to Vryburg where he landed. His wife then boarded the helicopter and from there they departed to FAWB The pilot was flying in a north-easterly direction into the rising sun at the time of the accident According to available evidence the pilot had on two previous occasions collided with an object aloft (wires) while flying the same helicopter The pilot was not wearing a flying helmet, he incurred severe head injuries during the impact sequence The helicopter was in possession of a valid certificate of airworthiness The last maintenance inspection prior to the accident flight was certified on 29 October 2014 at airframe hours. There were no recorded defects entered in the flight folio The main fuel tank was ruptured but the auxiliary tank still contained ample fuel No mechanical malfunction was detected during the engine teardown inspection The two occupants that were seated on the left side of the helicopter one survived CA 12-12a 07 FEBRUARY 2017 Page 24 of 33

25 the accident with minor injuries and the other with serious injuries The prevailing weather conditions had no influence on the accident Neither of the two occupants that survived the accident could recall seeing the tree prior to contact with it. 3.2 Probable cause The helicopter collided with a tree while on the descent for an intended landing, whereupon the pilot lost control and it impacted heavily with terrain. 3.3 Contributory factor Failure to keep a proper lookout by the pilot during a critical phase of flight. 4. SAFETY RECOMMENDATION 4.1 The safety message: Helicopter pilots should keep vigilance when approaching any landing area and ensure that they have identified or followed the unmanned aerodrome procedures when landing or taking off from such landing areas or aerodromes. 5. APPENDICES 5.1 Annexure A (Engine teardown report) CA 12-12a 07 FEBRUARY 2017 Page 25 of 33

26 ANNEXURE A The engine, a Lycoming IO-540-AE1A5, serial No. L E was removed from the wreckage after recovery and was taken to an approved engine maintenance facility where a teardown inspection was performed on Monday, 6 July The impact damage was of such a nature that the engine could not be subjected to a bench test. The sole purpose of the teardown inspection was to assess the mechanical integrity of the engine. The following observations were made: The engine prior to the teardown inspection Engine Model Serial No. Lycoming IO-540-AE1A5 L E Fuel Injector Servo, Precision Part # 61M23587 Serial # 70CR4403 The fuel injector servo sustained minor impact damage and was found to be in an overall good condition. A small amount of fuel was drained from the unit after it was removed from the engine. All linkages were secured and no anomalies were noted that would have restricted normal operation. CA 12-12a 07 FEBRUARY 2017 Page 26 of 33

27 Fuel pump The fuel pump was undamaged and was removed from the engine. The unit still contained a small amount of fuel. Fuel flow divider. Part # Serial # 4290 The fuel flow divider, with the six fuel lines attached, was found to be intact and the fuel lines were secured to the fuel nozzles. The wire locking was cut and the unit was opened. The unit did not display any internal damage and the diaphragm was found to be intact (see photograph). CA 12-12a 07 FEBRUARY 2017 Page 27 of 33

28 Fuel nozzles All six fuel nozzles were removed from the engine, inspected and found to be free of any obstructions. Spark plugs: Autolite UREM-38E The spark plugs were removed from the cylinders and found to be in good overall condition displaying a light brownish colour, which is associated with normal engine operation. The spark plugs on cylinders 2, 4 and 6 displayed evidence of oil on the electrodes, which was associated with the fact that the wreckage came to rest on its right-hand side and was lying in this position for several hours before it was placed in an upright position. HT harness Slick The high tension harnesses were in good overall condition. Magnetos Alpha Systems #66B21784 (right side), #66B21783 (left side) Both magnetos were still attached to the engine. The units did not sustain any damage and it was possible to bench test both units. The units were removed from the engine and were subjected to a bench test at an approved electrical maintenance facility. During the bench test both magnetos were found to function satisfactorily, providing spark over the entire RPM range it was tested. CA 12-12a 07 FEBRUARY 2017 Page 28 of 33

29 The left-hand magneto was found to be much noisier than the righthand magneto during the bench test procedure. The unit was dismantled following the bench test and it was found that the shaft bearing started showing evidence of wear. The photograph below display one of the magnetos being bench tested. Oil filter The filter was still attached to the engine and did not sustain any damage. Gear drive train The gear drive train was undamaged. Cylinders All six of the cylinders were removed, they showed signs of proper combustion and carbon deposits found to be normal on this type of engine. The #2 cylinder sleeve was found to be scored, which was attributed to wear caused over an undetermined period of time as a result of a broken compression ring on the #2 piston. CA 12-12a 07 FEBRUARY 2017 Page 29 of 33

30 Pistons & rings The pistons were in good condition and displayed evidence of carbon build-up associated with normal engine operation. Apart from the #2 piston compression ring (top ring) that failed no other damage was observed. The photo below displays the broken compression ring (top ring on the piston). Main bearings & Big-end bearings All the bearings were found to be in good overall condition and displayed evidence of adequate lubrication. Connecting rods LW All six connecting rods were found to be in good condition and the connecting bolts were properly secured. Crankshaft The crankshaft was found to be in good overall condition. In the photo below the connecting rods are still attached to the crankshaft. Both crankcase assemblies are also visible on the photo. CA 12-12a 07 FEBRUARY 2017 Page 30 of 33

31 Camshaft The camshaft including the gear drive assembly was removed. Several of the lobes on the camshaft displayed evidence of wear, with prominent wear evident on the number five lobe (see photo). CA 12-12a 07 FEBRUARY 2017 Page 31 of 33

32 Cylinder head/ valve assembly All the rocker covers were intact, the covers were removed and the valves with their associated valve springs were found to be intact and in good condition. Oil cooler The unit sustained minor impact damage. Oil pump The oil pump was found undamaged and in good condition. There were still several litres of oil inside the engine. CA 12-12a 07 FEBRUARY 2017 Page 32 of 33

33 Oil sump The sump sustained some impact damage but no oil leaked from the sump assembly. The oil pick-up was intact and free of any obstructions. The colour of the oil was black and had a very distinct smell. The black colour of the oil was associated with combustion gases bypassing the broken compression ring on the #2 cylinder piston. Starter The unit was attached to the engine but sustained some impact damage. Alternator The unit was attached to the engine but sustained some impact damage. Alternate observations The exhaust stacks were inspected and found to display a brownish colour on the inside, which could be associated with normal engine operation. Conclusion The teardown inspection of the engine did not reveal any pre- or post-impact mechanical failure that would have prevented the engine from normal operation. CA 12-12a 07 FEBRUARY 2017 Page 33 of 33