NTSB Identification: CHI96FA065.
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Accident occurred Saturday, December 23, 1995 in MORRIS, MN
Probable Cause Approval Date: 09/24/1996
Aircraft: MUMM LANCAIR, registration: N2114Z
Injuries: 2 Fatal.

NTSB investigators either traveled in support of this investigation or conducted a significant amount of investigative work without any travel, and used data obtained from various sources to prepare this aircraft accident report.

A witness who observed the airplane before the accident, saw the airplane 'performing a steep climb and then slowly turning left and coming back down. The airplane then straightened out and repeated the maneuver.' The airplane wreckage was discovered approximately 25 minutes later. The pilot/owner-builder told a friend the day before the accident that he intended to test the airplane to see how it would handle in stalls and stall recoveries. Examination of the wreckage revealed that the elevator bob weight was mounted on the idler arm upside down. A mock up of the assembly revealed the upside-down elevator bob weight was contacting the aft elevator push rod, resulting in a partial blockage of the elevator whenever forward stick controls were applied. This limited the elevator control surface to approximately 7 degrees of down elevator travel range. The assembly plans, provided by the kit manufacturer, were designed to provide a down elevator travel range of 13 degrees. The aircraft logbook indicated that as of 12/21/95, the airplane had logged 13.1 hours.

The National Transportation Safety Board determines the probable cause(s) of this accident to be:

the partially blocked elevator and improper installation of the elevator bob weight by the owner/builder which prevented full travel of the elevator control system. Factors relating to this accident were the intentional stall and inability to adequately recover from the stall.

Full narrative available

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