What happened
On September 10, 2023, a Bell 212 helicopter, registration N873HL, was involved in an accident near Balch Camp, California, while performing a Part 1 bypass firefighting flight under contract with the United States Forest Service. The pilot had completed eight water drops at altitudes between 6,000 and 7,000 feet mean sea level (msl) before returning to Sanger, California, to refuel.
During the mission, the pilot experienced several issues with the Simplex 304 Fire Attack System. During two water pickups earlier that day, the pump continued to run after the snorkel was withdrawn. Later, while refilling the tank at Pine Flat Reservoir, the pilot noticed water spilling from the tank. Although the pilot successfully cycled the tank power switch to move the doors, the system remained inconsistent.
While approaching a fire area located between 7,000 and 8,000 feet msl, the pilot noted the aircraft required more power than expected. To ensure a safe escape route, the pilot slowed the helicopter and attempted to jettison the water load. However, after two attempts to depress the drop switch, the tank doors failed to open. As the pilot increased collective control to turn toward a meadow, the low rotor rpm horn activated. The main rotor contacted a tree, causing the helicopter to descend rapidly and impact the ground, where a post-crash fire occurred. The pilot sustained one serious injury.
The investigation
Investigators examined the wreckage of N873HL, though the airframe and engines were heavily damaged by post-crash fire. The main drive shaft was intact but showed thermal damage and circumferential scoring. The main rotor blades showed no evidence of preimpact failure. Both engines were examined by the manufacturer and showed no evidence of mechanical anomalies that would have prevented normal operation.
An analysis of the pilot's load calculations revealed that the weight was calculated for a pressure altitude 2,000 feet lower than the accident site. While the pilot's initial calculation for the day's start suggested a permissible weight, the actual operating weight at the accident site—factoring in altitude, temperature, and fuel consumption—was estimated to be approximately 10,160 lbs. This was roughly 160 lbs over the maximum allowable weight of 10,000 lbs for the specific conditions at 8,000 feet msl and 20°C.
Findings
- The pilot's performance planning was inadequate, resulting in an excessive gross weight for the operating conditions.
- The helicopter was operating at its maximum performance limit, leading to a reduction in rotor speed and loss of lift during a turn.
- The pilot continued the flight despite experiencing multiple malfunctions with the water deployment system.
- The pilot was unable to successfully jettison the water load, which prevented a recovery from the loss of altitude.