Cessna 401 N9DM

Summary

On 11 May 2012 at about 21:30 local time, a Cessna 401 registered N9DM, operated by Private Individual, was involved in an accident near Chanute, Kansas, United States. 5 people were on board and 4 died, one was seriously injured. The aircraft was substantially damaged. The NTSB has published a probable cause for this accident; it is quoted in full below.

Date

11 May 2012 at 21:30

Classification

Accident

Location

Chanute, Kansas, United States

Coordinates

37.6383, -96.6131

Aircraft

Cessna 401

Registration

N9DM

Category

Airplane

Engines

2

Operator

Private Individual

Operating rule

Part 91: General Aviation

Purpose of flight

Personal

Phase of flight

Not recorded

Route

Tulsa → Council Bluffs

Aircraft damage

Substantial

Weather

VMC

Light

Day

NTSB number

CEN12FA290

4 people died.

The malfunction of the cabin heater, which resulted in an inflight fire and smoke in the airplane. Contributing to the accident was the pilot’s lack of understanding concerning the status of the airplane's heater system following and earlier overheat event and risk of its continued use. Also contributing were the inadequate inspection criteria for the cabin heater.

Quoted verbatim from the NTSB record. This site does not paraphrase or interpret it.

Read the full NTSB narrative

While en route to the destination airport, the pilot turned on the cabin heater and, afterward, an unusual smell was detected by the occupants and the ambient air temperature increased. When the pilot turned the heater off, dark smoke entered the cabin and obscured the occupants' vision. The smoke likely interfered with the pilot’s ability to identify a safe landing site. During the subsequent emergency landing attempt to a field, the airplane’s wing contacted the ground and the airplane cartwheeled. Examination of the airplane found several leaks around weld points on the combustion chamber of the heater unit. A review of logbook entries revealed that the heater was documented as inoperative during the most recent annual inspection. Although a work order indicated that maintenance work was completed at a later date, there was no logbook entry that returned the heater to service. There were no entries in the maintenance logbooks that documented any testing of the heater or tracking of the heater's hours of operation. A flight instructor who flew with the pilot previously stated that the pilot used the heater on the accident airplane at least once before the accident flight. The heater’s overheat warning light activated during that flight, and the heater shut down without incident. The flight instructor showed the pilot how to reset the overheat circuit breaker but did not follow up on its status during their instruction. There is no evidence that a mechanic examined the airplane before the accident flight. Regarding the overheat warning light, the airplane flight manual states that the heater “should be thoroughly checked to determine the reason for the malfunction” before the overheat switch is reset. The pilot’s use of the heater on the accident flight suggests that he did not understand its status and risk of its continued use without verifying that it had been thoroughly checked as outlined in the airplane flight manual. A review of applicable airworthiness directives found that, in comparison with similar combustion heater units, there is no calendar time limit that would require periodic inspection of the accident unit. In addition, there is no guidance or instruction to disable the heater such that it could no longer be activated in the airplane if the heater was not airworthy.

Quoted verbatim from the NTSB record.