Originally Posted by
MitchStick
https://app.ntsb.gov/pdfgenerator/Re...ctual&IType=FA
A "factual report" was published in October that, even if not final, seems to confirm Mast Bumping as cause.
Personally I'm somehow "relieved" for the fact that was a sadly well known cause and not some new design flaw that caused the crash..
Thanks Mitch for posting the accident report.
SPEED:
The factual report doesn't state the speed the R66 was flying last the time of accident. The iPad that was on board was found undamaged but couldn't be accessed as the device was password protected (
https://dms.ntsb.gov/pubdms/search/d...412&mkey=93446). However, the satellite track (
https://dms.ntsb.gov/pubdms/search/d...412&mkey=93446) as recorded by a SPOT device is included in the "Investigation Docket" referenced at the end of the Factual Report and invites for some analysis.
From the Factual Report:
A SPOT device, which is a handheld GPS tracking device that uses a satellite network enabling text messaging and GPS tracking services, was present on the helicopter. Records provided by the operator listed 19 location fixes beginning at Prescott at 1338 and proceeding on a southwesterly heading. The last data point at 1425 was in the vicinity of the accident site.
If you do the math, you find that the SPOT tracker was sending positions every 2.5 min (which is indeed one of the available SPOT settings: 2.5 min, 5min, or 10 min). As per the recorded track, the R66 was flying more or less straight, and constant average speed (the position points are on a straight line, and equidistant). If you average the speed over the 10 position reports before the accident (Position 4 to Position 14), you come the following result:
- Straight line distance 48 NM
- 25 min
-
Avg ground speed therefore 115 KT
- Track approximately 250° true
- Magnetic variation in Arizona approximately 10° East, therefore magnetic track approximately 240°
The Factual Report gives the wind (apart from significant turbulence that was reported by a R44 pilot operating on the area around the same time) as 190°, 17 gusting 22 KTS, as reported by a ground station 43 NM to the west of the accident scene. Not sure if wind direction is given in magnetic, or true? But it is fair to say that the mishap aircraft faced a certain headwind component, which means that the average true airspeed was slightly higher than the computed average ground speed of 115 KTS.
SPOT doesn't give altitude information.
WEIGHT:
Again, you have to look into the docket to find the a/c weight at the time of accident (
https://dms.ntsb.gov/pubdms/search/document.cfm?docID=457858&docketID=60412&mkey=93446). It is stated by the Operator of the flight (Guidance Air Service LLC) as 2,221 lbs. So that is not particularly light (consistent with 2 crew plus almost full fuel).
EXPERIENCE ON TYPE:
Both crew members were commercially rates pilots with thousands of hours. The Factual Report says that type-rated passenger (the operator's Part 141 chief pilot) was a helicopter-only pilot with over 5,000 HRS TTRW, but
only 101 HRS on type. And nil R66 HRS during the last 30 days before the accident.
Now, the PIC was a 8,000 HRS fix-wing ATP (single/multi engine). He was the operator's Part 135 chief pilot. While apparently rated on the R66,
neither his TTRW nor his time on type is filled in the operator's accident report (!).
These, in my opinion, critical numbers are also not stated in the Factual Report, nor is the unavailability of this information discussed. However, it was declared that
the PIC only did 10 HRS in helicopters over the past 90 days, thereof only 3 HRS in the past month (all in R66). He also was IF and instructor rated on helicopters.
I hope that the final accident report will dig deeper into what appears to be a "seasoned fix-wing pilot with comparatively low helicopter time flying a R66 in significant turbulence at high speed" scenario.