Mascari DISCOVERY S-12 N999

Summary

On 18 June 1994 at about 23:04 local time, a Mascari DISCOVERY S-12 registered N999, operated by Mascari, David M., was involved in an accident near Salinas, California, United States. One person was on board and one was seriously injured. The aircraft was destroyed. The NTSB has published a probable cause for this accident; it is quoted in full below.

Date

18 June 1994 at 23:04

Classification

Accident

Location

Salinas, California, United States

Nearest airport

Salinas Municipal (SNS)

Coordinates

36.6702, -121.6101

Aircraft

Mascari DISCOVERY S-12

Registration

N999

Category

Airplane

Engines

1

Operator

Mascari, David M.

Operating rule

Part 91: General Aviation

Purpose of flight

Unknown

Phase of flight

Not recorded

Aircraft damage

Destroyed

Weather

VMC

Light

Day

NTSB number

LAX94LA259

1 person was seriously injured.

THE FAILURE OF THE MUFFLER ASSEMBLY DUE TO PREEXISTING CRACKING IN THE OXIDIZED AREA OF THE WELD, WITH SUBSEQUENT DAMAGE AND SEPARATION OF THE PROPELLER AND REDUCTION GEAR BOX. A RELATED FACTOR WAS THE EXCESSIVE TAXISPEED WHICH RESULTED IN THE AIRPLANE BECOMING INADVERTENTLY AIRBORNE.

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

Read the full NTSB narrative

THE EXPERIMENTAL HOMEBUILT DISCOVERY S-12 AIRAILE INADVERTENTLY BECAME AIRBORNE DURING HIGH-SPEED TAXI TESTS. THE MECHANIC CONDUCTING THE TAXI TESTS WAS NOT A CERTIFICATED PILOT. HE CONTACTED THE TOWER AND INFORMED THEM OF HIS SUPRISE FLIGHT. WITHIN MOMENTS THE ENGINE FAILED, AND A FORCED LANDING WAS MADE IN A NEARBY FIELD. THE AIRPLANE COLLIDED WITH A STANDPIPE. WITNESSES REPORTED THAT THE PROPELLER, MUFFLER, AND REDUCTION GEARBOX HAD SEPARATED BEFORE THE AIRPLANE STRUCK THE STANDPIPE. EXAMINATION REVEALED THAT THE MUFFLER FRACTURED AT A FACTORY WELD; THE FRACTURE EXHIBITED EVIDENCE OF OXIDATION. THE MUFFLER THEN SEPARATED AS A RESULT OF NORMAL VIBRATION DURING OPERATION OF THE ENGINE. THE PROPELLER WAS DAMAGED AFTER THE MUFFLER STRUCK IT. THE DAMAGED PROPELLER WAS THEN OUT OF BALANCE, RESULTING IN THE REDUCTION GEARBOX SEPARATING FROM THE ENGINE.

Quoted verbatim from the NTSB record.