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."