ANC01LA066

The private certificated pilot was departing a river in a float-equipped airplane. During the takeoff run, the airplane came up on-step, but started to veer to the left. The pilot was holding full right rudder, but the airplane continued to turn left. He aborted the takeoff, but the left float collided with the bank of the river, and the right wing struck a tree. The airplane received damage to the left float assembly, the fuselage at the forward left float attach point, and the leading edge wing slat of the right wing. The float assembly was installed the previous month, 11.5 hours before the accident under a Supplemental Type Certificate (STC). Since the float installation, the pilot said he had trouble obtaining full right rudder travel of the aerodynamic rudder. After the accident, a mechanic found an incorrect set of springs, as part of the water rudder/aerodynamic rudder rigging, installed on the airplane. An FAA airworthiness inspector reviewed the tail spring concerns raised by the pilot. She found that the float installation STC specified the use of D-376 water rudder steering springs. Due to the lack of immediate availability, the installer used Scott 3200 tailwheel steering springs. The installer told the FAA inspector that due to the similarity of the two spring sets, he has utilized Scott 3200 tailwheel springs in the past on other float installations, utilizing FAA field approvals, and substitution of the springs have been widely used in the floatplane industry. In this case, the installer did not obtain an FAA field approval. The installer told the FAA that when the floats were installed on the accident airplane, the rigging of the water and aerodynamic rudders allowed proper movement of each assembly. The installer reported that the difference in the two spring assemblies, as measured by applying a 40 pound weight to each set, was 3/8 inch further extension of the D-376 springs.

On June 2, 2001, about 0930 Alaska daylight time, a float-equipped Helio H-391B airplane, N25BA, sustained substantial damage during an aborted takeoff from the Anvik River, about 21 miles northwest of Anvik, Alaska. The airplane was being operated as a visual flight rules (VFR) cross-country business flight under Title 14, CFR Part 91, when the accident occurred. The airplane was operated by Aurora Ventures Inc., dba Anvik River Lodge. The private certificated pilot, the sole occupant, was not injured. Visual meteorological conditions prevailed. VFR company flight following procedures were in effect.

During a telephone conversation with the National Transportation Safety Board (NTSB) investigator-in-charge (IIC), on June 11, 2001, the pilot reported he was planning to fly to Anvik to pick up cargo for the lodge. He said the float assembly was installed in May 2001, 11.5 hours before the accident under a Supplemental Type Certificate (STC), and since the float installation, he had trouble obtaining full right rudder travel of the aerodynamic rudder. The water rudders appeared to have sufficient travel. On the accident flight, the pilot said he was departing the Anvik River that was running about 4 knots of current. During the takeoff run, the airplane came up on-step, but started to veer to the left. He said he was holding full right rudder, but the airplane continued to turn left. He aborted the takeoff, but the left float collided with the bank of the river, and the right wing struck a tree. The airplane received damage to the left float assembly, the fuselage at the forward left float attach point, and the leading edge wing slat of the right wing.

The pilot reported that after the accident, he asked a mechanic from Anvik to inspect the airplane. The mechanic indicated an incorrect set of springs, as part of the water rudder/aerodynamic rudder rigging, was installed on the airplane. The mechanic installed the correct springs on June 12, 2001.

A Federal Aviation Administration (FAA) airworthiness inspector, Anchorage Flight Standards District Office, reviewed the tail spring concerns raised by the pilot. She found that the float installation STC specified the use of D-376 water rudder steering springs. Due to the lack of immediate availability, the installer used Scott 3200 tailwheel steering springs. The installer told the FAA inspector that due to the similarity of the two spring sets, he has utilized Scott 3200 tailwheel springs in the past on other float installations, utilizing FAA field approvals, and substitution of the springs have been widely used in the floatplane industry. In this case, the installer did not obtain an FAA field approval. The installer told the FAA that when the floats were installed on the accident airplane, the rigging of the water and aerodynamic rudders allowed proper movement of each assembly. The installer reported that the difference in the two spring assemblies, as measured by applying a 40 pound weight to each set, was 3/8 inch further extension of the D-376 springs.

According to the Pilot/Operator Report (NTSB form 6120.1/2) submitted by the pilot, the pilot indicated he had accrued 126.3 hours total time, of which 101.8 hours were accrued in the previous 90 days. The pilot accrued 66.1 hours in the accident airplane make and model, with 59.8 hours accrued in the previous 90 days.