CEN20LA041 · Cessna 525A
Cessna 525A · Accident: part(s) separation from aircraft en route
From Casper-Natrona County International Airport (CPR) to Western Neb. Rgnl/William B. Heilig Airport (BFF)
Event
- NTSB case
- CEN20LA041
- 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
- Accident
- 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
- Unknown
- 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 525A
- 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
- CGOJG
- Operator
- C-GHGR
- Onboard fatalities
- Unknown
- Route
- From Casper-Natrona County International Airport (CPR), Casper, WYTo Western Neb. Rgnl/William B. Heilig Airport (BFF), Scottsbluff, NE
- Aircraft age
- About 17 years (built 2002)
- 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
- Non-U.S., Non-Commercial
- 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 · cruise
- Defining eventThe 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
- Part(s) separation from aircraft
- DamageDestroyed: beyond practical repair. Substantial: damage that affects the structure, performance or handling and normally needs major repair. Minor: less than that. Glossary
- Substantial
Cause areas
- Aircraft › Aircraft handling/service
- Aircraft › Aircraft power plant
- Personnel issues › Task performance
Approximate · Coordinates as recorded by the NTSB; no uncertainty radius is established.
NTSB narrative
The airplane was in cruise flight at FL250 when it experienced a separation of the right engine cowl, which struck and substantially damaged the right horizontal stabilizer and elevator. The airplane landed at the destination airport without further incident. Postaccident examination of the airplane found that two fasteners located at the forward inboard corner of the right engine lower cowl and a third fastener (which joined the right engine upper and lower cowls) were missing. The cowling and three fasteners were not recovered.
Examination of the remaining fasteners used to secure the separated right engine cowl revealed that two were -4 studs, which were 0.03 inch longer than the other (-3) fasteners. The aircraft manufacturer’s drawings and the Illustrated Parts Catalog (IPC) for the engine lower cowl door indicated only -3 studs. Longer studs would allow for increased grip length, which would induce protrusion and misalignment of the engine cowl with adjacent structure. In addition, Skybolt grommets were used in the fastener assembly to secure the right engine lower cowl on the accident airplane; Skybolt grommets have a greater height than those cited in the IPC and the airplane manufacturer’s drawing, and, per these sources, Skybolt was not an approved vendor for the fastener assembly. The use of taller grommets would have also caused the cowl to protrude and be out of alignment with adjacent structure.
Postaccident photographs of the left engine lower cowl showed that it exhibited protrusion/mismatch (or misalignment) that exceeded aerodynamic smoothness requirements cited in the airplane structural repair manual. The left engine lower cowl had at least two -3 studs that were recessed below Skybolt grommets, which were located in the same area as that of the right engine lower cowl that had the three missing studs.
Without recovery of the right engine cowl, its aerodynamic smoothness could not be verified; however, using the observed postaccident condition of left engine cowl as an exemplar, available evidence suggests that the use of incorrect mounting hardware on the right engine
cowl would have similarly affected its aerodynamic smoothness. Therefore, the right engine cowl likely separated from the airplane due to the use of incorrect mounting hardware.
Probable cause
The installation of incorrect mounting hardware to secure the right engine cowl, which resulted in an in-flight separation and impact with the horizontal stabilizer and elevator.
Verbatim NTSB analysis and probable cause from the NTSB dataset
Sources
NTSB record CEN20LA041
- Event ID
- 20191224X95158
- Case number
- CEN20LA041
- Dataset
- full-current
- Source SHA-256
- 5cf380f0061817c0331a6b2d8cc7e0ee3a79bea469a1001dc5c10e56f35f5ab3
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, cause areas. 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: c793306f44baa041907f6a7836356c5a934831788813f80fdbe9419b03685fa1; retrieved 2026-09-16T10:49:02.574Z.