CHI96IA320 · Cessna 525
Cessna 525 · Incident: airframe, component or system failure en route
From General Mitchell International Airport (MKE) to General Mitchell International Airport (MKE)
Event
- NTSB case
- CHI96IA320
- Event typeAccident: someone killed or seriously injured, or the aircraft substantially damaged (NTSB definition). Incident: an occurrence that affected or could have affected safety, short of that. Glossary
- Incident
- InvestigationHow far the investigation had got when the record was published: preliminary, ongoing, final or completed. Unknown where the source does not say. Glossary
- Completed
- API-reported fatalities
- 0 · all aircraft and ground
- Ground fatalities
- 0
- OperationWhat kind of flying it was, grouped by the rules it flew under: airline (US Part 121), air taxi and commuter (Part 135), general aviation (Part 91 and similar), military or government. Glossary
- General aviation
- WeatherVisual meteorological conditions (VMC): good enough to fly by looking outside. Instrument conditions (IMC): cloud or low visibility, flying by instruments. Glossary
- Visual Meteorological Cond
Cessna 525
- Aircraft type
- Cessna 525
- Category
- Airplane
- RegistrationThe aircraft's tail number, such as N12345 or G-ABCD. Registrations are reissued, so the same one years apart can be a different aircraft. Glossary
- N123JN
- Operator
- Unknown
- Onboard fatalities
- Unknown
- Route
- From General Mitchell International Airport (MKE)To General Mitchell International Airport (MKE)
- Aircraft age
- Not recorded
- Flight rulesThe regulations the flight operated under: in the US, Part 91 (general aviation), Part 121 (airlines), Part 135 (air taxi and commuter) and others; for flights abroad, the NTSB's coarser commercial or non-commercial code. Glossary
- Part 91: General Aviation
- Phase of flightThe stage of the flight when things started to go wrong: standing, taxi, takeoff, initial climb, en route, maneuvering, approach or landing. Glossary
- En route · climb to cruise
- First occurrenceThe single coded event the NTSB judges best describes what happened (records from 2008 on). Older records name the first occurrence in the sequence instead. Glossary
- Airframe, component or system failure
- DamageDestroyed: beyond practical repair. Substantial: damage that affects the structure, performance or handling and normally needs major repair. Minor: less than that. Glossary
- Minor
Cause areas
- Turbine assembly, turbine wheel › Failure
Approximate · Coordinates as recorded by the NTSB; no uncertainty radius is established.
NTSB narrative
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.
Probable cause
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.
Verbatim NTSB analysis and probable cause from the NTSB dataset
Sources
NTSB record CHI96IA320
- Event ID
- 20001208X06434
- Case number
- CHI96IA320
- Dataset
- historical-pre2008
- Source SHA-256
- 89e2df6d848e7ab3b42e7d7c7a03ff403303057a26ca04c95b3ea67201c3ce74
Source notes (4)
- Unreviewed is an editorial label, not an investigation status. API-sourced is not report-checked or human-reviewed. Explicit event totals are used without summing aircraft injury tables; onboard allocation is withheld. Unknown values remain unknown. The operation category is mapped from the NTSB-reported FAR part and has not been reviewed.
- Filled from the NTSB case API where the bulk record had no value: investigation status. Values present in the bulk record are kept.
- The date is the local date, which is the same as the UTC date the NTSB stores.
- API snapshot SHA-256: 1cbb3b6b3e1786f9cbd9dc39ba02720e9f102247a1943233b995818d21d5d720; retrieved 2026-09-22T21:19:18.451Z.