What happened
The aircraft arrived at its destination and deplaned without incident. There were no indications of smoke, fumes, or heat during the flight. However, company maintenance personnel had previously placed damaged passenger seatbacks containing solid-state chemical oxygen generators in the forward cargo compartment along with seat covers and oil.
A company mechanic examined the seatbacks to locate a serviceable unit. During this process, he identified a loose oxygen canister and handled it improperly by gripping its oxygen hose. This action released the firing pin, which fired the percussion cap and triggered a chemical reaction that generated oxygen. The reaction produced heat reaching up to 430 degrees Fahrenheit outside the canister.
A fire subsequently began in the forward cargo compartment near where an oxygen canister was later found with a dented striker plate. The seat covers ignited, and the fire burned through the cabin floor before spreading throughout the entire cabin.
The investigation
Investigation revealed that company maintenance personnel were unaware that oxygen generators carried as company supplies were classified as hazardous materials. Additionally, the mechanic involved was not familiar with the repair or installation procedures for passenger supplemental oxygen equipment.
Findings
The primary causal factor was improper handling of an oxygen canister by a mechanic who lacked familiarity with the specific equipment. The lack of training regarding the hazardous nature of these generators contributed to the incident.