# NTSB CHI95IA030: Cessna 150, N7XC, Chesterfield, MO, October 26, 1994

- Type: NTSB incident investigation
- Classification: Incident · Minor injuries · Incident investigation · Final report
- Date: October 26, 1994, 18:00 local (23:00 UTC)
- Place: Chesterfield, MO
- Coordinates: 38.650093, -90.580207 (estimated)
- Nearby events: https://openairdocs.org/map.md?lat=38.6501&lon=-90.5802&mi=10
- Phase of flight: [Enroute](https://openairdocs.org/ntsb-phases/400) (OpenAirDocs' grouping)
- Highest injury: Minor injuries
- Injuries: 1 minor
- Status: Completed, report March 27, 1995
- Report: Approved by Office Director
- NTSB case key (mKey): 9754
- NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=CHI95IA030
- NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/9754/pdf
- Page: https://openairdocs.org/ntsb/CHI95IA030

## Probable cause

the cracked heater exhaust muffler which resulted from an improper repair.  Factors were the physical impairment of the solo flight student as a result of her inadequate training concerning carbon monoxide hazards.

## Sequence of events

In NTSB's coding before 2008 (https://www.ntsb.gov/GILS/Documents/codman.pdf).

- Airframe/component/system failure/malfunction, cruise - normal
  - exhaust system,muffler - cracked (cause)
  - maintenance,rebuild/remanufacture - improper, other maintenance personnel (cause)
  - physical impairment(carbon monoxide), pilot in command (contributing factor)
  - inadequate initial training, flight instructor(on ground) (contributing factor)

## Analysis

THE STUDENT SOLO PILOT RETURNED FROM A CROSS COUNTRY FLIGHT COMPLAINING OF HEADACHE, NAUSEA, AND DIFFICULTY WALKING. THE PILOT STATED THAT SHE HAD SMELLED EXHAUST FUMES, WAS NOT TAUGHT OF A POTENTIAL CONNECTION BETWEEN EXHAUST SMELLS AND CARBON MONOXIDE POISONING, AND CONTINUED THE FLIGHT.  MEDICAL TESTS REVEALED ELEVATED CARBON MONOXIDE, WHICH REQUIRED 5 1/2 HOURS OF 100% OXYGEN TO REDUCE TO NORMAL LEVELS.  POST-FLIGHT INSPECTION REVEALED A CRACK IN THE REPAIRED MUFFLER WHICH HAD BEEN INSTALLED 18 HOURS EARLIER.  THE PRIVATE PILOT PRACTICAL TEST STANDARDS REQUIRE THAT AN APPLICANT EXHIBIT KNOWLEDGE OF SYMPTOMS, EFFECTS, AND CORRECTIVE ACTIONS FOR CARBON MONOXIDE POISONING.

## Factual narrative

On October 26, 1994, at 1800 central daylight time, a student pilot returned from a solo cross country in a Cessna 150, N7XC, operated as a 14 CFR Part 91 training flight by Weiss Aviation of Chesterfield, Missouri.  The student complained she was nauseous, about to pass out, and had difficulty walking, but drove herself home.  Four hours later, after discovering an exhaust muffler crack (the repaired muffler had accumulated 18 hours in service since installation), the operator contacted the student and recommended she obtain medical attention.  Medical testing revealed an elevated blood level of Carbon Monoxide (17.5%).  After 5 1/2 hours of 100% Oxygen treatment, the CO concentration had reduced to 1.5% and the pilot was released.

The pilot stated that she had smelled fumes during the flight, was not taught of a potential hazard or connection between the smell and Carbon Monoxide poisoning, and continued the flight.

AC-61-21A, the Federal Aviation Administration Flight Training Handbook, discusses the hazards of Carbon Monoxide poisoning and faulty heater systems as a cause.  FAA-S-8081, the Private Pilot Practical Test Standards, requires under "Aeromedical Factors" that an applicant exhibits knowledge of symtoms, effects, and corrective action of carbon monoxide poisoning.

## Aircraft

- Registration: N7XC (not matched to a registry record)
- Reported make and model: CESSNA 150
- Category: Airplane
- Serial number: 15078099
- Airframe hours: 3822
- Engines: CONTINENTAL O-200-A 100 horsepower reciprocating
- Damage: No damage
- Flight: Instructional, Part 91
- Operator: Midwest Air Service, Inc., doing business as Weiss Aviation
- Registered owner: Midwest Air Service, Inc.
- Airworthiness certificate: Standard, Normal
- Last inspection: Unknown, October 11, 1994, 18 hours before
- Departed: SUS
- Destination: SUS
- Flight plan: VFR
- Airport: SUS, Spirit Of St. Louis

## Flight crew

As NTSB recorded them. NTSB leaves out names.

- Pilot; age 17; student; medical: class 3, valid medical--no waivers/lim.; seat: left; toxicology performed; flight hours: 43 total, 43 in this make and model, 20 in the last 90 days

## Weather

- Conditions: Visual (VMC), Day

## FAA reports on this event (1)

The FAA's own accident and incident reports, matched to the aircraft by N-number and date (OpenAirDocs).

- [Incident 19941026040109I](https://openairdocs.org/incident/19941026040109I), Oct 26, 1994: Cessna 150M, St Louis, MO. Odd smell. Became ill and nauseus. Returned to base. Discovered overhauled muffler cracked. Carbon monoxide cause.

From the NTSB's public API. Aircraft are matched to registry aircraft by N-number and event date, checked against the reported serial number, make and model; the registry's history has gaps, so older matches can be wrong. Compare the reported make and model.

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