Similar Issue A Factor In Two Other AS350 Downings

In its Preliminary Report issued this week on the March 8 downing of a Heli USA tour helicopter on the Hawaiian island of Kauai, the National Transportation Safety Board indicates the left lateral rotor control servo may have came lose from the main rotor blade -- potentially rendering the helicopter uncontrollable, and leading to the crash that killed four people and injured three.

Just before the accident, pilot Joe Sulak radioed he was "having hydraulic problems" and would attempt an emergency landing. A short time later, he told controllers the problem had degraded to hydraulic "failure."

Moments after that, Sulak made his last radio transmission before the helicopter impacted: "OK, we're done."

Sulak, one of the fatalities in the crash, came close to setting the helo down safely. As Aero-News reported, however, the helo pitched forward and fell to the ground alongside the runway at Princeville Airport. The impact crushed the forward portion of the AS350 AStar's cabin, and caused the helicopter's emergency floats to inflate.

In separate statements released this week, both the FAA and Eurocopter, manufacturer of the AStar, issued maintenance bulletins regarding the rotor control servo. The FAA states failure of a metal washer -- part of a component that prevents the servo from separating from the hydraulic servo-control rod -- can render the helicopter uncontrollable.

FAA spokesman Ian Gregor stressed its airworthiness bulletin was not related to the March 8 crash, as such notices are "some time in the making." The bulletins were in response to two earlier fatal accidents involving AStars, in which the servo problem was noted. The agency recommended operators immediately inspect their helicopters for similar defects.

In the Prelim, the NTSB notes the accident helicopter's hydraulic pump was intact. The fluid reservoir was full, but leaking from a fractured sight glass, possibly the result of impact forces.

"Further examination revealed that the lower clevis of the left lateral servo was still attached to the transmission case, but was no longer attached to the servo," the NTSB states. "Closer examination revealed that the threads on the clevis, as well as the threads on the inner diameter of the servo, appeared undamaged. The jam nut, the lock nut, and the safety wire were still attached to the clevis threads, and free to rotate."

Heli USA president Nigel Turner told the Honolulu Advertiser his mechanics immediately checked the rotor control servos throughout its AStar fleet, and did not find any problems like the one described in the NTSB Prelim, or by the FAA or Eurocopter.

"We checked the day after, and we went through all the fleet and we found nothing like this on any aircraft," Turner said. "I'm not a mechanic. I'm a pilot. And I can't make a comment at this time because it's early in an investigation."

FMI: Read The NTSB Preliminary Report