ERA09LA107

NTSB accident investigation · Moore David DM-1 · Salters, SC · December 25, 2008

Accident · Minor injuriesLimited investigationFinal report
Date
December 25, 2008, 14:50 local (19:50 UTC)
Place
Salters, SC
Injuries
2 minor
Damage
Substantial damage
Phase of flight
Maneuvering
Aircraft
N75EWMoore David DM-1
Defining event
Maneuvering: Flight control sys malf/fail
Weather
Visual (VMC) · Day
Status
Completed · report May 12, 2009
Report
Approved by Office Director
NTSB office
Eastern Region Aviation
Parties
FAA Columbia FSDO
FAA report
20081225856819A
Case key
73137

From the NTSB’s public API. By law, NTSB reports can’t be used as evidence in lawsuits over the accident.

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Probable cause

A hard landing following an autorotation that resulted from the separation of the red main rotor blade cap that led to the uncontrolled movement of the cyclic, autorotation and a hard landing.

Findings · 3

NTSB’s coded findings. Those marked are part of the probable cause; the rest are factors or other findings. Under each, the cases with the same finding.

Main rotor systemAircraft › Aircraft propeller/rotor · FailureMoore David DM-1: 1 caseAll aircraft: 25 casesProbable cause
Aircraft capability: maximum weightAircraft › Aircraft oper/perf/capability · Capability exceededMoore David DM-1: 1 caseAll aircraft: 152 cases

Sequence of events

The events NTSB coded, in order, by phase of flight. The defining event is the one that best describes the accident. Under each, the cases with the same event anywhere in their sequence.

Analysis

The pilot stated that while maneuvering at 800 feet above ground level, the homebuilt helicopter pitched up and slowed to 40 knots. He entered autorotation and the helicopter impacted the ground. Examination of the wreckage by a Federal Aviation Administration inspector revealed the end cap of the main rotor blade was missing. The inspector attributed the separation to excessive blade bowing due to taking off above maximum gross weight, resulting in a shift in the rotor blades center of gravity. The inspector also stated that the change of the blade's center of gravity created or aggravated the main rotor blades' twisting and balance reactance to such a level that the end cap of the red blade detached from the blade. This blade cap departure created an imbalance of the rotor blade that led to an out of balance and track condition of the main rotor resulting in a pitch up of the aircraft and loss of longitudinal control. Review of the helicopter logbook revealed the condition inspection was 8 months past the required 12-month inspection interval.

Factual narrative

On December 25, 2008, at about 1450 eastern standard time, an amateur built DM-1 helicopter, N75EW, lost control in flight and made a forced landing near Salters, South Carolina. The certificated commercial pilot and the passenger received minor injuries. The helicopter was substantially damaged. The flight was operated as a personal flight under the provisions of 14 Code of Federal Regulations (CFR) Part 91, and no flight plan was filed. Visual meteorological conditions prevailed at the time of the accident. The pilot stated that during a local flight he picked up his brother, serviced the helicopter with a full load of fuel, and then flew for approximately 3 hours. He said that while maneuvering he climbed to an altitude of 800 feet above ground level, and the helicopter, without command input, pitched up and slowed to 40 knots. He tried forward cyclic to lower the pitch attitude but was unsuccessful. He attempted to turn left and right but was, again, unsuccessful. He entered an autorotation and began to feel extreme lateral oscillations of the cyclic control. He continued by saying that the autorotation was almost vertical with no forward airspeed and in a nose high attitude. The helicopter impacted the ground and the pilot was ejected. Examination of the helicopter by a Federal Aviation Administration inspector revealed the end cap of the main rotor blade was missing. The inspector attributed the separation to an excessive blade bowing due to taking off above maximum gross weight, resulting in a shift in the rotor blades center of gravity. "The change of the blade's center of gravity created or aggravated the main rotor blades twisting and balance reactance to such a level that the end cap of the red blade detached from the blade. This blade cap departure created a radical shift in balance and drag of the rotor blade causing an out of balance and track condition of the main rotor resulting in a pitch up of the aircraft and lack of longitudinal control." Review of helicopter logbook revealed the conditions inspection was 8 months past the required 12-month inspection interval.

Aircraft

Registration
N75EW
Reported as
Moore David DM-1
Category
Helicopter, amateur-built
Serial number
1957
Engine
Lycoming O-360, 180 horsepower, reciprocating
Damage
Substantial damage
Flight
Personal · Part 91
Airworthiness certificate
Special, Experimental (Special)
Departed
CKI · Kingstree, SC
Destination
NONE · Salters, SC

Matched to the registry by N-number and the event date; the registry’s history has gaps, so older matches can be wrong. Compare the reported make and model.

Flight crew

As NTSB recorded them. NTSB leaves out names.

Role
Pilot
Age
34
Injuries
Minor
Certificate
Commercial
Airplane ratings
Single-engine land, Multi-engine land
Medical
Class 2, Without waivers/limitations
Seat
Left
Flight hours
6,000 total

Weather

Conditions
Visual (VMC) · Day
Wind
280° at 4 knots
Visibility
10 statute miles
Lowest ceiling
5,000 ft overcast
Temperature
70 °F, dew point 63 °F
Observed at
CKI, 15 nm away

FAA reports on this event · 1

The FAA’s own accident and incident reports, matched to the aircraft by N-number and date.