FTW99LA170 · Wsk Pzl Mielec M-18A
Wsk Pzl Mielec M-18A · Accident: airframe, component or system failure while maneuvering
From No airport to an unrecorded destination
Event
- NTSB case
- FTW99LA170
- 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
- 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
Wsk Pzl Mielec M-18A
- Aircraft type
- WSK PZL Mielec M-18
- 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
- N7075D
- Operator
- Unknown
- Onboard fatalities
- Unknown
- Route
- From No airportTo not recorded
- 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 137: Agricultural
- 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
- Maneuvering · aerial application
- 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
- Substantial
Cause areas
- Other maintenance personnel › Maintenance, not performed
- Wing, wing attachment fitting › Fatigue
- Wing, wing attachment fitting › Fractured
Approximate · Coordinates as recorded by the NTSB; no uncertainty radius is established.
NTSB narrative
The pilot was applying a chemical to a field. After completing a pass, as he applied aft elevator for a straight-ahead pull-up, a loud 'boom' was heard, and the outboard section of the right wing separated. The airplane became 'uncontrollable' and impacted in an uncultivated field. Metallurgical examination revealed that the separation of the right wing forward spar lower attachment fitting was the result of fatigue cracking in the bracket lugs. The fatigue cracking initiated from areas of severe corrosion damage in the lugs. Evidence of extensive corrosion pitting was found in brackets from all other examined front spar attachment fittings, particularly on the internal surfaces of the lugs. The Service Manual and applicable service bulletins call for fluorescent penetrant or magnetic particle inspection of wing attachment fittings during the 3,000-hour inspection for extension of the airframe life to 6,000-hours. Although the aircraft records show that during the last annual inspection, which was completed approximately 596.5 hours prior to the accident, at an airframe time of 4,245.5 hours, all time life items were complied with, the metallurgical examination disclosed no trace of dye penetrant residue on any of the examined components.
Probable cause
The separation of the right wing forward spar lower attachment fitting due to a fatigue fracture, which emanated from corrosion as a result of maintenance not being performed.
Verbatim NTSB analysis and probable cause from the NTSB dataset
Sources
NTSB record FTW99LA170
- Event ID
- 20001212X19004
- Case number
- FTW99LA170
- 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: 3973233fd3bba3cd64d895e04a11cd0cd007e742ab317ea328ab4590803d7933; retrieved 2026-09-21T20:30:14.397Z.