Cessna 525 incident near Milwaukee, Wisconsin, August 29, 1996
On August 29, 1996 at about 6:30 pm local time, a Cessna 525, registered N123JN, suffered minor damage in an incident near Milwaukee, Wisconsin. It was a business flight under general aviation rules (Part 91). No one was hurt; 3 people were on board or involved. The weather was visual conditions (good weather).
The NTSB's probable cause their words, unchanged
an uncontained failure of a high pressure turbine disk blade retention post due to fatigue. A factor relating to the incident was: inadequate design of the high pressure turbine disk. Fretting on the leading side of the lobe near the fracture origin may have contributed to premature initiation of the fatigue.
Source: NTSB aviation accident database, copy made October 5, 2026. Docket and reports at the NTSB.
What the record shows
- Date
- August 29, 1996 · about 6:30 pm local time
- Place
- Milwaukee, Wisconsin · map
- Type
- Incident
- Injuries
- No one was hurt; 3 people were on board or involved.
- Weather
- visual conditions (good weather)
- Aircraft
- Cessna 525 · all 525s on the register
- Registration
- N123JN · no longer on the register · serial 46
- Damage
- Minor damage
- Flight
- Business flight · general aviation rules (Part 91)
The NTSB's narrative final · quoted from the NTSB record
After being cleared to climb from 6,000', the pilot began advancing the throttles to climb power, when he heard a loud bang & noted indications of a #2 engine failure. He secured the #2 engine & made an uneventful landing. Examination of the failed Williams-Rolls FJ44-1A engine revealed it had sustained an uncontained high pressure turbine (HPT) disk blade retention post failure. Examination of the HTP disk (PN 48629) showed that a blade retention post had fractured adjacent to the bottom of the blade slots & that 3 adjacent HPT blades had broken loose. Subsequently, the upper portion of the fuel-oil heat exchanger mount pad was fractured, which resulted in an oil leak. Metallurgical examination revealed the primary failure was the release of a blade retaining lobe just below a fret zone. Creep fatigue was found at the failed blade retaining holes. No evidence of gross overheating was noted. The failed disk was of an 'older' design. As a result of the incident, Williams-Rolls Alert Service Bulletins No. FJ44-A72-30 and -31 were issued to describe a procedure for eddy current inspection (ECI) of the high pressure turbine (HPT) disk blade retention posts to locate possible cracks and to describe a procedure for replacing the existing HPT disks with an advanced-design HPT disk. Also, Airworthiness Directive (AD) 97-01-05 was issued to require initial and recurring ECIs of the HPT disks and for replacement of FJ44-1A HPT disks with improved disks. A more durable fuel-oil mounting pad was being developed for the FJ44-2 engine.
The complete narrative as the NTSB published it. The NTSB's docket holds the report as a PDF and any photographs, statements and other documents from the investigation.
The factual record from the NTSB's investigation tables, in plain English
Pilot
- Certificate: airline transport pilot, commercial pilot
- Ratings: multi-engine land; single-engine land; instructor: airplane multi-engine; instructor: airplane single-engine; instructor: instrument airplane; instrument: airplane
- Flight time: 11,783 hours in all; 785 in this make and model; 85 in the last 90 days; 32 in the last 30 days; 11,314 as pilot in command; 1,400 on instruments
- Medical certificate: Class 1 (valid medical--no waivers/lim.)
- Seat: left
The aircraft
- Airframe total time: 708 hours
- Last inspection: continuous airworthiness programme, December 31, 1995; 110 hours since
- Maximum gross weight: 10,400 lb
- Seats: 8
- Landing gear: retractable
- Engine: Williams Intl FJ44-1A (turbofan); 0 hours total
The flight
- Departed from: MKE
- Destination: MKE
- Flight plan: IFR
- Runway 0
Weather at the time
- Light: daylight
- Sky: not recorded; not recorded
- Temperature: 0°F (-18°C), dew point 0°F (-18°C)
Injuries
| Fatal | Serious | Minor | None | |
|---|---|---|---|---|
| Crew | 1 | |||
| Passengers | 2 |
Documents from the investigation the NTSB's docket: the evidence folder behind the report
The docket, the folder of records gathered during an investigation (maintenance records, photographs, witness statements, examinations), has not been read from the NTSB for this case yet; the list appears here once it has. Open the docket at the NTSB.
Other NTSB records under N123JN the same tail number, which may have belonged to a different aircraft at the time
Everything on this page comes from the NTSB's public records. The narrative, probable cause and findings are the NTSB's own words; the coded tables behind the report are written out in plain English, with pilots' ages, home towns and medical details left out. The documents and photographs are the NTSB's docket, shown as the NTSB released them. This site's own text never names anyone involved. A preliminary report can change; the final report usually follows one to two years later, and the page is refreshed when it does.