AS 355 F1 S/N 5168 Factual Report Iao Valley Maui, Hawaii Date: July 21, 2000

Transcription

1 AS 355 F1 S/N 5168 Factual Report Iao Valley Maui, Hawaii Date: July 21, 2000 Note: Any and all references throughout this factual report to damage found during the wreckage inspection is not intended to imply the damage noted was the cause or a contributing factor to the accident. Ken Arnold Manager Accident Investigation 1

2 Directly below the arrow is the Iao Valley, 9miles west of the Kahului Heliport where this photo was taken. The Iao Valley has the reputation of being the second wettest place on earth in terms of average rainfall. 2

3 This photo is the crash site, the arrow at the top points what is the helicopters initial point of impact. The blue object at the bottom of the picture is the tailboom which is approximately 200 ft. below the initial impact point.the clearing in the trees was made by the helicopter wreckage, parts of which were found scattered down the clearing. 3

4 The right cabin door was crushed in the direction of the arrows both up and aft. The windscreen center post and the right windscreen post, just forward of the door were separated from what remained of the canopy structure. 4

5 The left cabin door was crushed at the same angle as the right cabin door (shown on page 4). The forward cross tube,( in this photo, under the left cabin door) is bent forward at the lower attach points for the skid tubes. The cross tube is normally at a 90 degree angle to the ground or skid tube. 5

6 Left hand aft cabin flap door crush angles are consistent with those of the forward cabin doors. The hinge and part of the airframe structure are still attached to the door, and appear to be crushed at the same angle as the main cabin doors. 6

7 Both right and left skid tubes were broken off forward of the cross tube, dirt was packed in the ends of both skid tubes. The forward cross tube was found buried in the soil at the crash site, and had to be extracted by digging. 7

8 NR/NTL Indicator face found separated from the case and needle. 8

9 Both oil temperature and aft fuel quantity indicators were unreadable. The indication needles for each of these instruments were broken. 9

10 The collective pitch jack shaft was broken away from the supporting structure. The collective pitch control was broken off of the jack shaft, just forward of the friction adjustment threads on the collective pitch control. (arrow points to break) The main and tail rotor controls and tubes located in and under the cabin received fire damage. 10

11 Pilot s cyclic and pedals were bent forward and burned. A small portion of the cabin floor is still attached to the base of the cyclic. Control continuity could not be determined due to the damage present. 11

12 Dual NG Gauge was found with the No.1 Engine needle at 71% NG and No. 2 Engine needle at 67% NG. The glass covering the instrument face was found broken at the time of the aircraft recovery. 12

13 Artificial horizon indicator, stopped with an almost level pitch attitude and a slight left bank angle. 13

14 Altimeter face, was set at Hg, the altitude indicated did not match the elevation of the impact mark, which was 2900 ft. above sea level, according to the USGS map and hand held Global Positioning system used by the NTSB investigator. The remaining parts of this instrument were destroyed. 14

15 The curved arrow indicates the direction of rotation of the main rotor head and blades. The straight arrow indicates the angle of the break of the starflex arm. The star and all sleeves received fire damage. 15

16 Two main rotor blades were still attached to the sleeves. The star arm attached to the main rotor blade on the right, was broken. The star arm for the blade in the center, of the picture was not broken but did receive fire damage. 16

17 The main rotor pitch rods were broken and fire damaged and did not appear to be bent. The curved arrow shows direction of rotation of the main rotor head. The block arrow shows the star arm break direction. 17

18 This starflex arm was broken in the angle opposite the break of the star arm directly trailing it. The break of this star arm has larger portion of material remaining on the leading edge, less material remaining on trailing edge. 18

19 Upper arrow shows the third star arm is not broken off, however it is drooping from fire damage. The lower arrow points to the Pitch rod and horn, which are not broken or bent. 19

20 This picture shows no rotational damage to the upper and lower scissors links. The entire main rotor head and gearbox sustained fire damage. 20

21 Both fore and aft and right side servo input rods were complete, only damage present was from fire and bending of the rods at impact. Control continuity below the transmission deck could not be confirmed due to impact damage. 21

22 Left input to combining gearbox was broken off at the center of the C-box case.(arrow pointing down) Tail rotor output pinion gear could be turned and would turn the main rotor head. Both Coupling tubes were broken at both ends (arrow pointing left). C-Box S/N M5136, Bevel reduction S/N M5141, Epicyclic S/N 384, M/R Shaft S/N M580 22

23 Left hand input drive to combining gearbox shows no rotational scars or spline damage where the engine to main gearbox input drive shaft exited drive system during the accident. The input shaft was not found the recovered parts. The flex coupling in this picture was slightly distorted towards the front of the aircraft. 23

24 Right hand input drive to combining gearbox shows no evidence of rotational scaring or spline damage. Flex coupling is distorted (bent forward). This coupling could be rotated and would rotate the main rotor head through the transmission gears. The engine to combining gearbox shaft for the right side was not found in the recovered parts. 24

25 Tail rotor output shaft was broken at the main gearbox end of the shaft. The break was a compression type. The drive shaft also sustained fire damage. 25

26 Tail rotor output shaft from main gearbox to oil cooler fan assembly was found wrapped up in the engine firewall/fan air tunnel. This picture also shows the top of the engine deck with the right hand engine mount detached in a forward direction. 26

27 Engine deck and center structure was crushed from the front and bottom, this section came to rest 200 ft. down the mountain from the initial impact point Both engines were detached from this structure(engine deck) and it sustained fire damage. The right hand engine received the more fire damage than the left engine. 27

28 The main rotor blade in the center was broken at station 1000, and sustained leading edge damage inboard from the tip. This blade was found detached from the main rotor head with the sleeve and pins attached to the blade. This blade also sustained the least fire damage of all three blades, the trailing edge of this blade was also detached the entire length of the blade. Blade S/N s 4279, 3806, 3856 were not readable on the blades due to fire damage. 28

29 The Lower blade in the photo broke at station 1000 and near the midpoint of the blade. The leading edge strips are damaged from fire and blade breaking, the trailing edge of the blade is separated from the blade spar. The burned section of the blade was still attached to the main rotor head sleeve and star, and the star flex arm was broken. 29

30 This is the outboard end of the blade in the previous picture on page 29, the tip cap is missing and the leading edge has an impact mark indicated by the arrow. The trailing edge of the blade is separated from the spar and rovings. Dirt was present in the impact damage on 2 of the main rotor blades. 30

31 This main rotor blade was burned the entire length and broken at station 1000, the tip cap is peeled aft. There is no evidence of leading edge impact damage on the outboard end of this blade, and the trailing edge is separated like the other two main rotor blades. 31

32 The tailboom was separated aft of the fuselage junction frame, and the vertical fin assembly was separated from the tailboom at the tail cone. This section was found in the trees 200ft. below the initial impact area with no fire damage. 32

33 This view is the break line of the forward end of the tailboom. The hole or tear indicated by the arrow had some wood fibers in it. The tailboom break was at the second tailboom reinforcement ring. 33

34 The tail rotor drive shaft bearings are all shifted forward out of the mounts.(note: horizontal arrow) The shaft had one compression break between the no. 5&6 bearings at the point indicated by the vertical arrow. The #6 driveshaft bearing and shaft are under the driveshaft for visual placement purposes, they were not found this way. 34

35 This photo is of the tail driveshaft in the previous picture on page 34. The arrow points to the forward end of the shaft. The shaft was both bent upwards and broken at this point. This break is a compression type break. 35

36 The flexible coupling is distorted but not broken, the tailboom and tail control tube have some damage just underneath the flexible coupling. As indicated by the arrow, the front tail gearbox mount is broken and pushed forward. Rotational scars on T/R control tube, (arrow), which is also compressed. 36

37 The tail rotor gearbox would still rotate, and no chips were found on the magnetic plug upon it s removal. The pitch control continuity was established from the control rod on the tailboom to the tail rotor blade horns, and the spider assembly had no damage. TGB S/N M192 P/N 350A

38 Tail rotor pitch links and horns had no visible damage. Control continuity from the spider to pitch horns was demonstrated. 38

39 One side of the tail rotor blade was broken at the cuff, and half way down the blade.(arrows) Both sides of the blades were bent in a slight curve from the root and had some delamination of the skin. 39

40 This picture of the tail rotor blade shows the bend in a flapping direction, that occurred in both ends of the tail rotor blades. 40

41 Both strike tabs were bent flat against the tip of the blade and slightly aft towards the trailing edge. The leading edges of the blade had light surface scratches. No other impact marks were present. Blade S/N 7676 P/N 355A

42 The vertical fin assembly and tail cone were detached from the tailboom. The lower vertical fin was bent up and back (arrow direction), tail skid had only a slight bend up. The rivets at forward attachment doublers were sheared. 42

43 The top of the engine cowl was separated from the cowl doors. The right engine cowl and baggage door had fire damage inside and outside. The left side had fire damage on the inside only. The top of the engine cowl was located away from the doors at the crash site. 43

44 Both aft cross tube attachment points were rotated aft 90 degrees as indicated by the arrow. The aft cross tube mounts were still located in the proper position laterally. 44

45 The fuel tank structure was ruptured, and both fuel quantity probes were broken and crushed flat. 45

46 This is engine No. 2 after disassembly by Rolls Royce. The accessory gearbox, fuel control, and governor were destroyed by fire. Engine No. 2, 250-C20F S/N CAE (TSO 990.6) Engine No. 1 (Not shown ), 250-C20F S/N ( TSO ) 46

47 This report was compiled at the request of the National Transportation Safety Board to record the damage to aircraft S/N This aircraft crashed on July 21,2000 near 10:20 AM Hawaiian standard time. The crash occurred on the Island of Maui, in the mountains surrounding the Iao Valley. The photos in this report were taken after the subject aircraft was placed in a storage hanger at Kahului, Airport. Operation type: Sightseeing Tour FAR part 135. FAA Registration: N510TG Aircraft Model: Eurocopter AS355F-1 Helicopter Date of Manufacture: 1982 Pilot: Larry Kirsch, Total time 12,000+ reported Certificate# Operator: Blue Hawaiian Helicopters GPS coordinates: 20 degrees 52.3 minutes north by 156 degrees 34.9 minutes west. 47