Tl Ultralight Sro STINGSPORT N898N

Summary

On 1 September 2012 at about 17:30 local time, a Tl Ultralight Sro STINGSPORT registered N898N, operated by STING4FUN LLC, was involved in an accident near Longmont, Colorado, United States. 2 people were on board and nobody was injured. The aircraft was substantially damaged. The NTSB has published a probable cause for this accident; it is quoted in full below.

Date

1 September 2012 at 17:30

Classification

Accident

Location

Longmont, Colorado, United States

Coordinates

40.2178, -105.0103

Aircraft

Tl Ultralight Sro STINGSPORT

Registration

N898N

Category

Airplane

Year built

2006

Engines

1

Operator

STING4FUN LLC

Operating rule

Part 91: General Aviation

Purpose of flight

Personal

Phase of flight

Not recorded

Route

Erie → Erie

Aircraft damage

Substantial

Weather

VMC

Light

Day

NTSB number

CEN12LA655

Nobody was injured.

The failure of the wood propeller blades in flight. Contributing to the accident was the owner/operator’s failure to complete required inspections on the propeller within the specified interval, which reduced the likelihood of detecting the cracks and may have contributed to the crack growth.

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

Read the full NTSB narrative

While conducting maneuvers at 2,500 feet, the airplane began to vibrate violently. The pilot aborted the maneuver and retarded the throttle to idle; the engine experienced a total loss of power. The pilot executed a forced landing into a field. After the landing, the pilot and the designated pilot examiner noticed that two of the propeller blades had separated from the propeller hub. An examination of the fractured blades and blade sleeves revealed that blade A likely fractured due to progressive cracking at laminate bonds at the interface between the wood blade and the metal sleeve. The powdery wood observed in the slots and at the root end of the blade shank were indicative of rubbing wood as the cracks progressed. The blade B fracture was likely secondary and occurred due to the vibrations associated with the imbalance created by the blade A fracture and subsequent separation. The propeller log indicated that manufacturer-specified visual inspections and torque checks were not conducted at the specified interval of 150 hours but at intervals of about 203, 320, and 250 hours. The delayed visual inspections reduced the likelihood of detecting the cracks and the delayed torque checks might have contributed to crack growth in the blade.

Quoted verbatim from the NTSB record.