Willow Creek, CA, USA
N613CK
CROMAN SH-3H
The pilot-in-command (PIC) of the firefighting helicopter air tanker reported that he approached the heliwell (a portable tank) by entering a final approach from the south as he had on four previous trips that day. As he lowered the snorkel into the heliwell to get water, he simultaneously made a right pedal turn to position the helicopter for a normal egress departure path. He indicated that all engine parameters were in the normal operating range, that he did not feel any unusual movements in the flight controls, and that the wind seemed to be light and variable. As the helicopter was taking on water, the second-in-command (SIC) called out the number of gallons in the tank, and the PIC released the fill switch at the planned amount. The PIC applied power and initiated a climb just as the snorkel was clearing the water. At this time, the SIC informed the PIC of a "droop" in the rotor rpm. Subsequently, the PIC stopped applying power and started to move the helicopter forward. The SIC then called out that the rotor rpm was at 98 percent. The PIC reduced the power slightly to gain rpm, but the rpm continued to drop. The PIC leveled the helicopter as it continued to descend. The left main landing gear subsequently contacted the heliwell then the uneven ground. The helicopter rolled after ground contact and came to rest on its left side. The PIC did not activate the emergency dump button, which was located on the top left side of the collective, and the SIC did not pull the emergency "T" handle to jettison the load during the accident sequence. Postaccident examinations of the engines and fuel controls found no mechanical malfunctions or failures that would have precluded normal operations.
HISTORY OF FLIGHT On July 17, 2009, about 1510 Pacific daylight time, a Croman SH-3H, N613CK, collided with terrain at a heliwell site near the Willow Creek Hellibase, Willow Creek, California. The United Stated Forest Service (USFS) was operating the helicopter under the provisions of 14 Code of Federal Regulations (CFR) Part 137. The USFS had contracted with the Croman Corporation for the services of the helicopter. The commercial rated first pilot was designated by the contractor as pilot-in-command (PIC), and was not injured. The commercial rated second pilot was designated by the contractor as second-in-command (SIC), and sustained minor injuries. The helicopter rolled onto its side and sustained substantial damage to the main rotor blades, fuselage, and tail rotor. The local public-use flight departed the Willow Creek helibase about 1416 on a fire fighting mission. Visual meteorological conditions prevailed, and a company flight plan had been filed. The contractor reported that the helicopter was utilizing a snorkel system to fill an internal tank. The snorkel drew water from a heliwell (a 5,000-gallon portable tank); the term for filling the internal tank with a snorkel was "drafting." The crew had successfully completed four circuits; the accident occurred on the fifth. On the third trip, the PIC utilized the common practice of jettisoning some of the water to reduce gross weight, which allowed the helicopter to transition to forward flight as it exited the heliwell. On the accident flight, the PIC was at the controls, and flying from the left seat. He stated that he approached the heliwell as he had the prior four trips by entering a final approach from the south. As he lowered the snorkel into the heliwell, he simultaneously made a right pedal turn (nose right) to a southerly heading for a normal egress departure path. On the accident flight, the PIC stated that the helicopter had taken on 400 to 450 gallons of water, which was the same amount as previous flights. As he applied power, the helicopter started to climb clear of the heliwell. He stated that as the snorkel came out of the water, the SIC called out droop several times. The PIC said that he stopped applying power, and started to move forward. The SIC called out that they were at 98 percent. After the PIC reduced collective slightly to gain rotor rpm (Nr), the SIC again called out droop a couple of times. The PIC stated that Nr continued to fall, and might have gone as low as 92 percent. He tried to drop the load, but was not sure that he actually activated the dump switch. Witnesses observed the left main landing gear make contact with the heliwell. The PIC stated that he leveled the helicopter as it continued down toward uneven ground; the helicopter rolled after ground contact, and came to rest on its left side. The SIC exited through his bubble window; the PIC shut off the firewall valves and battery switches, and then exited the helicopter. The SIC did not remember making the droop callout in a postaccident interview. PERSONNEL INFORMATION Pilot-in-Command The contractor reported that the 65-year-old PIC held a commercial pilot certificate with a rating for rotorcraft-helicopter, and private pilot certificate with a rating for airplane single-engine land. He had type ratings for SK-61 and BV-107. The PIC held a second-class medical certificate issued on July 10, 2009. It had the limitations that the pilot must wear corrective lenses, and possess glasses for near and intermediate vision. The contractor reported that the PIC had a total flight time of 21,000 hours. He logged 30 hours in the last 90 days, and 30 in the last 30 days. He had an estimated 9,000 hours in this make and model. He completed a proficiency check on March 7, 2009. Second-in-Command The contractor reported that the SIC held a commercial pilot certificate with a rating for rotorcraft-helicopter and instrument helicopter. He had a certified flight instructor certificate with a rating for rotorcraft-helicopter. He was type rated in the SK61. The SIC held a second-class medical certificate issued on March 2, 2009. It had no limitations or waivers. The contractor reported that the SIC had a total flight time of 2,554 hours. He had 865 hours in this make and model. He logged 38 hours in the last 90 days, and 38 in the last 30 days. He completed a proficiency check on February 3, 2009. AIRCRAFT INFORMATION The helicopter was a Croman SH-3H, serial number 152109. The operator reported that the helicopter had a total airframe time of 14,354 hours at the time of the accident. It had a continuous airworthiness inspection on July 17, 2009. The left engine was a General Electric T58-402, serial number 281-323. Total time recorded on the engine was 8,946 hours, and time since major overhaul was 68 hours. The right engine was a General Electric T58-402, serial number 281-778. Total time recorded on the engine was 7,612 hours, and time since major overhaul was 192 hours. The helicopter's weight was indicated to be 11,405 pounds according to its weight and balance (W & B) Chart "C" form 14. It departed the Willow Creek helibase with approximately 3,300 pounds of fuel. After the accident, the investigation team weighed the remains of the helicopter to validate the weight & balance form. The result of the weighing was 11,446.25 pounds actual weight, a weight gain of 40.95 pounds. TESTS AND RESEARCH Engine Exams The engines were examined with no discrepancies detected. Fuel Control Exams Both fuel control units were tested at Columbia Helicopter, Inc., in accordance with the Audit Acceptance Tests under the supervision of a National Transportation Safety Board investigator. The results indicated that they did not contribute to the accident sequence. ADDITIONAL INFORMATION Supplemental Type Certificate The helicopter operated under a Supplemental Type Certificate (STC) with regard to the internal firefighting tank system. The system included an internal tank and an external 18-foot-long snorkel. Hover/Snorkel Operations There was an emergency water release "T" handle located just aft of the center console. It was a mechanical/manual handle that would open the tank doors to the full open position for an emergency salvo situation. The contractor stated that there was no written training procedure in place for drafting (snorkel) operations. It was common practice that the SIC should have their hand near or on the emergency water/retardant release in case of an emergency. If there was an emergency or in the case of Nr droop, the SIC could pull the emergency "T" handle to dump the load. During a post accident examination, investigators observed the emergency water release "T" handle in the stowed position. The SIC stated that he did not have his hand near the emergency "T" handle, and that this was never pulled during the accident sequence. Both water tank doors appeared to be in their closed position. PIC The PIC stated that he and the SIC had made four previous trips to the heliwell. He approached the heliwell, and made a right pedal turn to position them for egress. He indicated that all engine parameters were in the green normal operating range, he did not feel any unusual movements in the flight controls, and the wind seemed to be light and variable. The left side of the collective contained a fill/dump toggle switch that was spring located to the center (off) position; forward was to dump, and aft was to fill. A red emergency salvo button was on the top left side of the cyclic. The PIC stated that as the helicopter was taking on water, the SIC called out the number of gallons in the tank, and the PIC released the fill switch at the planned amount (400 gallons). He applied power, and initiated a climb out as the snorkel was clearing the water. At this time, the SIC informed him of a droop condition; the PIC stopped applying power, and felt the helicopter settle. He did not activate the emergency dump button; he was unsure if he activated the dump switch. SIC As water was being drafted, the SIC was responsible for monitoring the instrument panel with his primary concerns being Nr and torque. He was also responsible for calling out water quantity levels so the PIC, (who had his attention out of the cockpit looking down and back at the snorkel, tank and tail rotor) was aware of how much water they had onboard. The PIC would call out that they were in position and taking on water. The SIC stated that he had to turn around in his seat, and look over his left shoulder to read the quantity gauge located on the tank. The SIC's responsibilities were to confirm that they were initially taking on water and then call out when the tank had the desired amount of water. The SIC indicated that fill time to the intended water level was typically no more than 10 seconds. He would then turn back around, and look at the engine gauges. Croman Policy Croman reported that their procedure was to determine torque available in a hover at the altitude and temperature of the dip site. The pilot was to save a minimum of 10-20 percent torque for takeoff depending on the conditions, regardless of the amount of water in the internal tank. Prior to committing to takeoff, the pilot must insure that the snorkel was well clear of the heliwell.
The pilot’s failure to maintain adequate power during egress from a heliwell, which resulted in collision with the heliwell and a dynamic rollover.
Source: NTSB Aviation Accident Database
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