Hall Lester R LEGACY N707MM
20 July 2023 · Rochester, Minnesota, United States · No injuries
Summary
On 20 July 2023 at about 19:42 local time, a Hall Lester R LEGACY registered N707MM was involved in an incident near Rochester, Minnesota, United States. 2 people were on board and nobody was injured. The aircraft was slightly damaged. The NTSB has published a probable cause for this accident; it is quoted in full below.
The record
- Date
- at 19:42
- Classification
- Incident
- Location
- Rochester, Minnesota, United States
- Nearest airport
- Rochester International Airpor (RST)
- Coordinates
- 44.0573, -92.5062
- Aircraft
- Hall Lester R LEGACY
- Registration
- N707MM
- Category
- Airplane
- Year built
- 2003
- Engines
- 1
- Operator
- Not recorded
- Operating rule
- Part 91: General Aviation
- Purpose of flight
- Air Race/Show
- Phase of flight
- Not recorded
- Route
- Rapid City → Rochester
- Aircraft damage
- Minor
- Weather
- VMC
- Light
- Day
- NTSB number
- ENG23LA034
People
Nobody was injured.
| On board | Died | Serious | Minor | Uninjured |
|---|---|---|---|---|
| 2 | 0 | 0 | 0 | 2 |
Probable cause
Mechanically distressed reduction gears causing an engine overspeed and turbine blade tensile overload and subsequent uncontainment. Contributing to the uncontainment was the operator’s use of the engine after knowingly purchasing the engine in an unserviceable condition and only conducting a periodic inspection before flight.
Quoted verbatim from the NTSB record. This site does not paraphrase or interpret it.
Read the full NTSB narrative
The teeth of the 1st stage sun gear in the reduction gearbox were ground away in the plane of the mating gear teeth of the 1st stage planet gears. The mating gear teeth of the three planet gears were battered and fractured. Distress of the 1st stage sun gear teeth released the torque normally transferred to the propeller, causing the power turbines to overspeed and the power turbine blades to release in tension and become uncontained. It was unknown when the last inspection of the reduction gearbox was performed. During the post incident examination of the engine at the P&WC facility, the engine was found to be in poor overall condition with missing surface protective paint and surface corrosion noted throughout the external and internal surfaces of the engine. A review of the purchase documentation revealed that the operator knowingly purchased the engine in unserviceable condition and only performed a periodic inspection before flight.
Quoted verbatim from the NTSB record.
Other accidents in this area
| Date | Aircraft | Location | Operator | Outcome | Died |
|---|---|---|---|---|---|
| 25 Feb 2023 | Cessna 172S | Princeton, Minnesota, United States | Twin Cities Flight Training, Inc | No injuries | - |
| 27 Jun 2023 | Schweizer G-164B | Beltrami, Minnesota, United States | Gasper Air Spray, Inc | Fatal | 1 |
| 11 May 2023 | Loehle Acft 5151 MUSTANG | Hector, Minnesota, United States | - | No injuries | - |
| 17 Sep 2023 | Cessna 150K | South Saint Paul, Minnesota, United States | - | No injuries | - |
| 30 Jun 2023 | Icon A5 | Onamia, Minnesota, United States | - | Fatal | 1 |
| 12 Mar 2023 | Socata TB21 | Eden Prairie, Minnesota, United States | - | Serious injuries | - |