FTW01LA166

The twin-engine helicopter departed on a positioning flight to pick up a medical patient. While in cruise flight, at 2,000 feet, both engines experienced a total loss of power. The pilot attempted to autorotate to a field; however, the helicopter impacted trees and came to rest on its right side. The pilot reported that he did not notice any warning lights immediately prior to or during the loss of engine power events. However, it was noted during a post-accident examination of the helicopter that the pilot instrument light and console light variable resistor control was in the ON position. This control dims the master caution and annunciator panel lights for night operations. The NTSB IIC noted that the master caution and annunciator lights were not visible in daylight with the pilot and console variable resistor control in the ON position. Although the two fuel transfer pump switches were found in the ON (normal operating) position, examination of the fuel system provided evidence that the dual engine power loss was the result of fuel starvation due to these switches not being ON during the majority of the flight. The fuel supply lines to the engines were found empty, a nominal amount of fuel was found in the fuel filters, and the fuel quantity indicator displayed 4, 0, and 15 gallons of fuel in the #1 supply, #2 supply, and forward main fuel tanks, respectively. The function of the fuel transfer pumps is to transfer fuel from the forward main tank to the two supply tanks. The fuel transfer pumps were operated during the post-accident examination by turning on their respective switches and it was noted that fuel began to flow into the supply tanks. Additionally, it was noted that the fuel transfer pump caution lights (which are illuminated when the pumps are off) extinguished when the pumps were turned on. The engines were placed in a test cell and both operated with no anomalies noted. The normal operating checklist calls, in part, for the pilot to set the instrument lights as required, test the annunciator panel for operation, and turn on the transfer pumps after engine start.

History of accident

On July 20, 2001, at 1603 central daylight time, a Eurocopter BK117-C1 twin-engine helicopter, N313LS, was substantially damaged when it impacted trees and terrain during an autorotation following a dual loss of engine power while in cruise flight near Decatur, Texas. The helicopter was registered to Debis Financial Services, Inc., of Norwalk, Connecticut, and was operated by Omniflight Helicopters, Inc., of Addison, Texas. The commercial pilot and flight nurse sustained serious injuries, and the flight paramedic received minor injuries. Visual meteorological conditions prevailed and a visual flight rules (VFR) company flight plan was filed for the 14 Code of Federal Regulations Part 91 positioning flight. The flight originated from Dallas, Texas, at 1535, and was destined for Wichita Falls, Texas.

The flight was en route to Wichita Falls to pick up a medical patient. According to the operator, the pilot reported that shortly after flying past Decatur, Texas, the helicopter experienced a loss of engine power on the #2 (right) engine. The pilot stated that he secured the engine and started to divert to the Decatur Municipal Airport. During the diversion, the #1 (left) engine lost power and the pilot attempted to autorotate the helicopter to a field. The helicopter impacted trees adjacent to the field and came to rest on its right side.

A witness, who worked for the U.S. Forest Service and was driving near the accident site, observed the helicopter pass over his automobile. He then observed the helicopter "make a 180-degree turn to the east. There was no smoke and [he] assumed that the aircraft had landed in a field." Shortly after the helicopter disappeared from his view, the witness received a radio call concerning an aircraft accident. Approximately 30 minutes after observing the helicopter, the witness found the accident site; however, no one was there. The operator reported that they had airlifted the pilot and crew out of the accident site prior to the local authorities' arrival.

Review of the operator's dispatch audio tape revealed that the flight had departed Dallas at 1535:33, and the pilot reported having 2 hours and 20 minutes of fuel on board and an estimated time en route of 1 hour and 20 minutes. Between 1552:06 and 1553:09, the dispatcher attempted to obtain a position report from the pilot to no avail. At 1553:25, the pilot gave a position report. At 1555:46, the dispatcher provided a patient update to the pilot and medical crew. At 1603:35, a radio squelch was heard over the tape; however, no voice transmission was recorded. Between 1609:09 and 1610:07, the dispatcher attempted to obtain a position report from the pilot; however, she was unsuccessful. At 1610:42, the dispatcher received a cellular phone call from the flight's paramedic stating that they had been involved in an accident and they were requesting medical assistance. The paramedic reported that the pilot had made a mayday call; however, the dispatcher never heard it.

During an interview conducted by an NTSB investigator, the flight paramedic reported that on the morning of the accident, he arrived at work at 0545. He and the flight nurse performed their preflight checks. Both the paramedic and nurse reported that they had not seen whether or not the pilot conducted a preflight inspection of the helicopter. The medical crew received a call around 1530, notifying them of a patient who was to be picked up in Wichita Falls. The paramedic and flight nurse then conducted a "walk around" prior to departing, and the paramedic performed the fire guard duties for the engine start. The paramedic reported that the pilot started the right engine first. Neither the paramedic nor the nurse noticed whether the pilot was utilizing the checklist during the engine start procedures.

The paramedic was sitting in the front left seat during the flight. He reported that while they were en route, he noticed that the torque indicators were at 40% and 70%. He asked the pilot if that was alright and the pilot then matched the torque indicators. When the flight passed Decatur, at an altitude of 2,000 feet, the audio warning sounded, which the pilot then cleared. The paramedic added that the audio warning sounded again and he noticed a master caution warning light and 3 annunciator lights. He stated that the lights were dim and he could not read them.

The pilot announced to the paramedic that they were flying single-engine and were diverting to Decatur. The pilot requested that the paramedic confirm that they had lost power on the #2 engine, which he did. Subsequently, the pilot secured the #2 engine and asked the paramedic for the emergency procedure checklist; however, the paramedic "interrupted him." The paramedic reported that they were in a turn and descending when he noticed the left engine torque gauge "drop to zero from about 70%." The aircraft was in a "high rate of descent over trees about 100-150 feet agl heading for a clearing," and the pilot made a mayday call. The paramedic added that he did not notice the fuel quantity, did not hear or smell anything unusual, and approximately 40-50 seconds had elapsed between the two loss of power events.

The pilot stated to the NTSB investigator-in-charge (IIC) that he did not see any warning lights immediately prior to, or during the loss of engine power events.

Personnel information

The pilot held a commercial helicopter certificate with an instrument helicopter rating. On May 25, 2001, the pilot was issued a second class medical certificate with a limitation to "possess corrective glasses for near vision." According to company flight records, the pilot underwent initial BK-117 training with Omniflight Helicopters on July 31, 1999, and underwent his last recurrent ground and flight training in the BK-117 on February 19, 2001. According to the Pilot/Operator Aircraft Accident Report, the pilot had accumulated 6,411.8 total hours of rotorcraft flight time, of which 292.8 hours were in the BK-117. Review of the company's airman flight and duty time record revealed that the pilot worked from 0630 to 1900, on the both the 18th and 19th of July. On the morning of the accident, the pilot started his work shift at 0630.

Aircraft information

The accident helicopter was configured for the transport of medical patients with two seats in the cockpit, two rear-facing seats aft of the cockpit, one medical bed, and a bench. The helicopter was powered by two Turbomeca ARRIEL 1E2 turboshaft engines. The helicopter's fuel system utilizes four bladder type fuel cells: a forward main tank, an aft main tank, and two center supply tanks. The aft main fuel tank supplies fuel to the forward main fuel tank via a gravity feed system. The fuel is then routed to the left and right fuel supply tanks via two transfer pumps (forward and aft) located in the forward main fuel tank. The left supply tank provides fuel for the left engine, and the right supply tank provides fuel for the right engine. The fuel system has a usable fuel capacity of 1,230.39 pounds (181 gallons) of jet fuel, and a total unusable fuel quantity of 7.7 pounds (1.1 gallons) in the main fuel tanks and 10.143 pounds (1.49 gallons) in the supply fuel tanks. The fuel quantity indicator displays the fuel quantity in the forward main fuel tank and the two supply fuel tanks. Additionally, there is a fuel low sensor installed in each supply tank, which illuminates a FUEL LOW I and/or II caution light on the annunciator panel if the fuel in a supply tank becomes lower than 49.39 pounds (7.26 gallons).

In part, the helicopter's flight manual calls for the following steps during the pre-start checklist:

FUEL PUMP TRANSFER switches - ON (F PUMP XFER caution light off)

FUEL PUMP TRANSFER switches - OFF (F PUMP XFER caution light on)

PRIME PUMPS caution light - Check function in turn: