Two weeks after the loss of CHI91 and 17 of the 18 souls on board, the Transportation Safety Board concluded the field phase of its investigation today by releasing some details of the crash.
Among the highlights:
- The cause of the gearbox oil pressure loss has been determined to be an in-flight break of a stud in the gearbox filter assembly as previously released.
- The aircraft descended rapidly from 800 feet above sea level (ASL) in under a minute owing to an as-yet undetermined event. Estimated rate of descent is given as 1,000 feet per minute.
- The aircraft struck the water upright (belly first) in a tail down attitude. This is different from earlier reports that the aircraft may have struck nose first. That conclusion was apparently based on an initial assessment of the fuselage, as recovered. The new interpretation is based on an examination of the entire wreck plus flight data. Some comment the day the main portion of the aircraft was brought ashore suggested that the tail rotor assembly (rotor plus vertical fin) had broken from the tail boom. The boom was broken from the main fuselage.
- Two of the three flotation devices in the aircraft were recovered undeployed. The only one to deploy appears to have been under the starboard pilot station (co-pilot position?). The right forward floatation bag can be seen in a TSB photo of some of the wreckage released earlier this week.
- The timeline is very similar to the one previously posted here. The MAYDAY call came at approximately 5500 ASL which is at about 0817 hours Eastern Daylight Time in the flightaware.com tracklog.
- The aircraft experienced an unexplained loss of power while at 800 ASL. This resulted in a lack of flight data from the aircraft’s onboard recorders. The last two to three minutes of the flight have been reconstructed using other data, including onshore radar records.
- The pilot did indicate his intention to ditch from 800 ASL.
- Force on the aircraft at impact is estimated at 20g.
More to follow.
-srbp-