Pilot Debrief

ROBINSON HELICOPTER R22 BETA II near North Las Vegas, NV — 2011-03-11

Final reportWPR11LA161
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Date
2011-03-11
Location
North Las Vegas, NV, USA
Airport
KVGT
Aircraft
ROBINSON HELICOPTER R22 BETA II
Registration
N8360T
Category
Helicopter
Highest injury
None
Fatalities
0
Phase of flight
Hover

Probable cause

The partial loss of engine power for undetermined reasons. Contributing to the accident was the certified flight instructor's decision to continue the flight after the helicopter exhibited inadequate performance capabilities and an unresolved power production issue.

NTSB narrative

While conducting the pre-takeoff check of the right magneto, the certified flight instructor (CFI) determined that the drop in the helicopter's engine rpm remained within operational limits during the required two-second check period, but that it continued to drop significantly for a short period thereafter. A second check sequence produced the same results. Although concerned, the CFI continued the instructional flight, whereupon he determined that maneuvering the helicopter was taking considerably more power than he was accustomed to. About 30 minutes into the flight, the CFI landed the helicopter to once again check the right magneto because of the apparent lack of performance. The results showed the same excessive post-check rpm drop. After lifting the helicopter back airborne, and returning control to the student in a low hover, the helicopter suddenly descended, contacting the surface with one skid. The CFI then took control of the helicopter, but was unable to keep it from rolling onto its side. A postaccident test and disassembly inspection of the helicopter's magnetos and ignition system did not reveal a reason for the rpm drop or the reduction in performance.

Analysis

Primary failure mode
Human factors
First missed decision gate
Instructor should have terminated the flight after the second magneto check.

NTSB coding

Evidence available

  • 4 docket documents
View NTSB final reportView NTSB docket

Docket documents4

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