- Date
- February 1, 1991, 12:30 local (20:30 UTC)
- Place
- Agua Caliente, CA
- Injuries
- 2 serious
- Damage
- Substantial damage
- Phase of flight
- Enroute
- Aircraft
- N17SRiddell Lancair 235
- Weather
- Visual (VMC) · Day
- Status
- Completed · report March 31, 1993
- Report
- Approved by Office Director
- FAA report
- 19910201003529A
- Case key
- 27107
From the NTSB’s public API. By law, NTSB reports can’t be used as evidence in lawsuits over the accident.
On this page
Probable cause
The failure of the propeller blades due to a weakening of the wood structure due to acid hydrolysis. A factor in the accident was the inadequate maintenance of the propeller assembly by allowing exposure to excessive moisture and heat.
Sequence of events
NTSB’s coding before 2008: each occurrence and phase of flight, and the causes and factors under it. The codes are defined in NTSB’s coding manual.
Analysis
The aircraft was on climb out when a loud bang was heard, followed by an engine overspeed then engine stoppage. After the forced landing, the pilots found that both wooden propeller blades had separated from the steel hub assembly. The propeller hub was removed from the engine and sent to the manufacturer for functional analysis and disassembly under the supervision of FAA inspectors. The manufacturer stated that all internal components were functional, however, the cam adjustment for the high and low pitch stop settings had been altered from the factory settings. The blade butt ends retained in the hub were removed and submitted to the forest products laboratory of the us department of agriculture for analysis. According to the laboratory the wooden blades fractured and separated due to a hydrolysis interaction between the wood and the adhesive caused by excess moisture and heat. The hydrolysis is a chemical decomposition process of the wood and glue relationship.
Aircraft
- Registration
- N17S
- Reported as
- Riddell Lancair 235 (LANCAIR 23)
- Category
- Airplane, amateur-built
- Serial number
- OJ-1988
- Engine
- Lycoming O-320, 160 horsepower, reciprocating
- Damage
- Substantial damage
- Flight
- Personal · Part 91
- Operator
- Kenneth E. Parks
- Registered owner
- Kenneth E. Parks
- Last inspection
- Unknown · January 2, 2000
- Departed
- MYF · San Diego, CA
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
- 47
- Certificate
- Airline transport
- Airplane ratings
- Single-engine land, Multi-engine land
- Instrument ratings
- Airplane
- Medical
- Class 1, Valid Medical--no waivers/lim.
- Flight hours
- 1,500 total · 400 in this make and model · 4,500 as pilot in command
Weather
- Conditions
- Visual (VMC) · Day
- Wind
- 90° at 15 knots
- Visibility
- 10 statute miles
- Lowest ceiling
- None
FAA reports on this event · 1
The FAA’s own accident and incident reports, matched to the aircraft by N-number and date.