ASN Wikibase Occurrence # 315167
This information is added by users of ASN. Neither ASN nor the Flight Safety Foundation are responsible for the completeness or correctness of this information.
If you feel this information is incomplete or incorrect, you can submit corrected information.
| Date: | Tuesday 9 May 2023 |
| Time: | 17:50 |
| Type: | Rans S-21 Outbound |
| Owner/operator: | Private |
| Registration: | N468MM |
| MSN: | 06180007 |
| Fatalities: | Fatalities: 0 / Occupants: 1 |
| Aircraft damage: | Substantial |
| Category: | Accident |
| Location: | Creswell, OR -
 United States of America
|
| Phase: | Manoeuvring (airshow, firefighting, ag.ops.) |
| Nature: | Private |
| Departure airport: | Creswell, OR |
| Creswell, OR | |
| Investigating agency: | NTSB |
| Confidence Rating: |  Information verified through data from accident investigation authorities |
On May 09, 2023, about 1750 Pacific daylight time, a Rans homebuilt airplane, N468MM, was substantially damaged when it was involved in an accident near Creswell, Oregon. The pilot, the sole occupant, was not injured. The airplane was operated as a Title 14 Code of Federal Regulations Part 91 personal flight.
The pilot and his son had recently finished building the airplane. The accident flight was a series of test flights the pilot was performing after making cowling modifications. After a normal departure, the pilot flew to a test area and was inflight for about 20 minutes. While the pilot was maneuvering about 700-900 feet above ground level (agl), the engine made “rough” sounds and vibrated. About 20 seconds later, the propeller seized, and the pilot made a forced landing in the field below. During landing roll out, the airplane flipped over and came to rest inverted damaging the vertical stabilizer (see Figure 1 below).
The UL Power 520T six-cylinder engine was new when installed on the airplane and had amassed a total time of about 55 hours. The pilot noted that for the last approximate 20 hours of engine operation, the engine monitoring unit showed that the cylinder head temperature (CHT) in the Nos. 3 and 4 cylinders were high (occasionally the Nos. 2, 4, and 6 cylinders would also be high). In response, the pilot changed to a larger oil cooler and was modifying the cowling to increase airflow.
Investigators conducted a postaccident examination of the wreckage which included a complete disassembly of the engine. The cowlings had been removed and a trace amount of oil on the bottom cowling was noted in the area under the Nos. 2,4,6 cylinders. Removal of the top spark plugs revealed that all showed signatures that the engine representative stated were consistent with normal operation.
Investigators were unable to rotate the crankshaft by hand utilizing the propeller; it would only rotate a few degrees before binding. Clean, uncontaminated oil was observed at all six rocker box areas. Removal of the cylinders revealed that the combustion chambers and pistons were undamaged.
The turbocharger compressor and turbine wheel could both rotate. The wastegate bango fitting was finger tight at the wastegate and tight at the boost valve. The turbocharger compressor and turbine wheel spun freely. The housing on the turbine side was green/bluish.
Removal of the oil sump drain revealed that the magnetic plug was full with ferrous metal and metal pieces were found in the oil sump. The oil pump was disassembled and there was limited metal found inside, with the exception of the bypass spring.
Upon applying force to the propeller, the engine would not rotate through. Removal of the pistons revealed that the crankshaft was fractured at a web, just aft of the journal of the No. 2 connecting rod. The thrust bearing mount was able to move forward and aft.
Disassembly of the crankcase revealed that the six connecting rod journals still had their respective rods and caps attached; all were able to be easily rotated about their respective journals (see Figure 2 below).
The fracture exhibited a half-moon shape, having proceeded through approximately half the web. The fracture surface was relatively shiny and reflective, with some areas of heat tinting on the forward face. The preliminary assessment of the fracture surfaces were consistent with a fatigue fracture at the radius on the connecting rod journal (see Figure 3 below).
The crankshaft was sent to the NTSB Materials Laboratory for further analysis and the Electronic Control Unit (ECU) will be downloaded.
Accident investigation:
 |
|
Sources:
NTSB
Revision history:
| Date/time | Contributor | Updates |
|---|---|---|
| 12-Jun-2023 20:28 | Captain Adam | Added |
Corrections or additions? ... Edit this accident description
The Aviation Safety Network is an exclusive service provided by:
Quick Links:
| ASN Home | Send Correction / Feedback |
| FSF Home | Disclaimer | Copyright |
| Contact Us | Privacy Policy |
| Press / Media |
CONNECT WITH US:
©2024 Flight Safety Foundation