Adler SA-1 N551SA

Summary

On 8 September 2002 at about 15:30 local time, a Adler SA-1 registered N551SA was involved in an accident near Mead, Colorado, United States. One person was on board and one died. The aircraft was destroyed. The NTSB has published a probable cause for this accident; it is quoted in full below.

Date

8 September 2002 at 15:30

Classification

Accident

Location

Mead, Colorado, United States

Coordinates

40.2142, -104.9503

Aircraft

Adler SA-1

Registration

N551SA

Category

Gyrocraft

Engines

1

Operator

Not recorded

Operating rule

Part 91: General Aviation

Purpose of flight

Personal

Phase of flight

Not recorded

Route

Broomfield → Unknown

Aircraft damage

Destroyed

Weather

VMC

Light

Day

NTSB number

DEN02LA103

1 person died.

the pilot's failure to maintain main rotor rpm, resulting in blade flapping, subsequent blade contact with the airframe, and loss of control.

Quoted verbatim from the NTSB record. This site does not paraphrase or interpret it.

Read the full NTSB narrative

Witnesses observed "a rotor or a wing" separate from the gyroplane, and the gyroplane then descended and impacted terrain. According to the deputy's report, a rotor blade was found about 150 feet north of the point of impact, and other debris was strewn to the southwest. The co-builder of the accident gyroplane, who was also a close friend of the pilot, contacted three gyroplane experts: the designer of the SA-1 Dominator and President of Rotor Flight Dynamics; a gyroplane aerodynamist; and the designer of another gyroplane. They examined the wreckage and compiled both a factual and analytical report. The following is based on the factual portion of the report. The separated rotor blade was bowed upward and had fractured about 2 feet from the tip. The fracture was consistent with positive overload. There was orange paint and primer transfer marks on the top and upper leading edge (the tail cone was painted orange). The attached rotor blade was also bent upward. The propeller blades exhibited no strike marks. The rotor head and hub bar were intact. The hub bar, normally bent 2.5 degrees upward, was bent approximately 10 degrees upward. The roll pillow blocks bore evidence of hammering and were mushroomed. The pitch stops were similarly damaged. In the analytical portion of the report, the necessity of maintaining blade loading at all times in order to maintain main rotor blade rotation was noted. The fracture on the separated main rotor blade was in "a purely upward bending moment which could only have occurred if the blade rpm had dramatically slowed...If totally unloaded, the blade rpm can deteriorate as fast as 120 rpm/sec." Normal rotor blade rpm is 320 to 400 rpm. If rotor blade rpm were allowed to drop, increasing the velocity of air moving through the rotor system, severe blade "flapping" would result as evidenced by the pounding and mushrooming of the roll pillow blocks and bending of the hub bar on the rotor head. A toxicological test revealed 2.024 (ug/mL, ug/g) paroxetine in the blood and liver. The drug is an antidepressant and contraindicated for flight. The pilot's personal physician prescribed the drug for the treatment of fibromyalgia, a condition manifested by muscle soreness. Adverse effects of the drug include drowsiness, muscle weakness, agitation, and tremors.

Quoted verbatim from the NTSB record.