Aviation Accident Summaries

Aviation Accident Summary SEA04FA143

Cle Elum, WA, USA

Aircraft #1

N1912H

Piper PA-28-140

Analysis

The pilot, who had loaded the aircraft to a weight more than 100 pounds over the maximum permissible takeoff gross weight, did not perform either weight and balance or takeoff/climb performance calculations prior to takeoff. He then attempted a takeoff and climb-out in a high density altitude environment, but was unable to maintain a rate of climb sufficient to clear nearby trees without his airspeed dropping to near that at which a stall would occur. After passing through an opening in a line of trees he could not climb over, the pilot elected to attempt to return to the airport. While in a shallow turn, the aircraft came in contact with a tree, which resulted in it loosing enough altitude that it was unable to clear another group of trees between it and the airport. Seeing that he could not clear the trees, the pilot elected to attempt a controlled crash landing in an area between some of the trees, but one of the aircraft's wing impacted one of the trees while the aircraft was still about 15 feet above the ground.

Factual Information

HISTORY OF FLIGHT On July 24, 2004, approximately 1850 Pacific daylight time, a Piper PA-28-140, N1912H, impacted a tree about one-half mile southwest of Cle Elum Municipal Airport, Cle Elum, Washington. At the time of the accident, the pilot was maneuvering at a very low altitude in an attempt to get back to the Cle Elum Airport. The private pilot and one of his passengers received serious injuries, one passenger received fatal injuries, and one passenger received minor injures. The aircraft, which is owned by Zephyr Aviation, and operated by Noland-Decoto Flying Service, was substantially damaged. The14 CFR Part 91 personal pleasure flight, which departed Cle Elum Airport about three minutes before the accident, was being operated in visual meteorological condition. No flight plan had been filed. It is unknown whether there was an ELT activation. On the day of the accident, the pilot had scheduled the aircraft for a flight at 1000, but there was reportedly a mix-up in scheduling and the operator had planned on using the aircraft for student training until about 1400. Therefore, the pilot rescheduled the aircraft for 1600 that same afternoon. He arrived at the airport about 1600, completed his preflight inspection, and was ready for departure by 1645. During the preflight inspection, the pilot detected a small amount of sediment in the fuel drain samples he took, but he did not consider this significant, so he continued preparation for the flight and entered a comment about the sediment in the aircraft rental log. After his initial takeoff, the pilot performed one touch-and-go landing at Yakima, and then departed for Tieton State Airport, where he made a low approach (simulated touch-and-go), and then climbed out to the north en route to Cle Elum. The flight arrived at Cle Elum about 1820, after which the pilot shut the airplane down, did a walk-around inspection, loaded and briefed his passengers, and then took off on runway 25 because there was a slight headwind on that runway. According to the pilot, during the takeoff he held the nose down slightly longer than normal "...in order to obtain as much airspeed as possible before rotation." Almost immediately after rotation, the aircraft lifted off, but the pilot was unable to establish a positive rate of climb, and the stall warning horn began to sound. He said that after the aircraft passed the west end of the runway, he realized its climb rate may not be sufficient to clear a tree line about one-half mile west of the airport, so he increased the aircraft's pitch attitude in an attempt to increase its climb rate. With the stall warning horn continuing to sound, and with the aircraft still not appreciably increasing its climb rate, the pilot started looking for a way to get past the tree line. He soon saw a location a short distance to the north where there was an opening in the trees, and therefore maneuvered the aircraft through that opening. Since the aircraft still did not seem to be climbing, the pilot initiated a very shallow-banked turn to the left in order to attempt to get back to the airport. During the turn, the stall warning horn kept sounding, the airspeed slowly started to drop, and according to the pilot, the aircraft's left wing contacted a tree. After contacting the tree, the aircraft seemed to stall, and the pilot lowered the nose in order to recover. He was ultimately able to get the aircraft pointed back toward the airport, but he could not see the runway environment because the aircraft was so low that another line of trees blocked his view. As he approached the these trees, he realized that he was not going to clear them, so he maneuvered the aircraft to a location that allowed him to attempt a controlled crash landing without impacting the nearby houses and barns. When he was about 20 feet above the ground, the pilot "flared" the aircraft in order to minimize the forward speed, and almost immediately thereafter the aircraft impacted a tree. It then contacted the ground and slid to a stop at the base of another tree. Soon after the aircraft came to a stop, a small fire broke out in the engine compartment, and the pilot, once out of the aircraft, threw dirt on it in order to put it out. WRECKAGE AND IMPACT INFORMATION The aircraft impacted the tree about 15 feet above the ground, and then traveled on a heading of about 300 degrees magnetic before impacting the ground about 40 feet past the tree. It then slid approximately 170 feet before coming to a stop inverted at the base of another tree. The right wing had separated from the fuselage near the wing root, and it had been torn into two pieces just inboard of where the outboard end of the flap butts up against the inboard end of the aileron. The leading edge of the wing had been crushed directly aft at this point, and both the skin and the inner structure had been torn on a line from the leading edge to the trailing edge. Except for the right wing and the outboard half of the right horizontal stabilizer, which had also been torn off by tree impact, the entire aircraft was located at the base of the aforementioned tree. The flaps where found in the up position, and in a post-accident interview, the pilot stated that although he thought about putting the flaps in a partially extended position prior to takeoff, he had not done so. During a post accident inspection of the engine, mechanical continuity was established from the pistons through the crankshaft to the accessory section and valve train. In addition, during propeller rotation each magneto and wiring harness produced spark at both the upper and lower row of spark plugs on the left and right cylinder banks. During this same test, the creation of compression in each cylinder was established by placing a thumb over the associated spark plug hole. There were no unusual contaminants on the spark plugs and no significant accumulation of lead. The plug electrodes showed no unusual wear, and there was no evidence of electrode insulator cracking. The carburetor was disassembled, and there was no evidence of any contamination, sediment buildup, component wear, or any functional anomaly. In addition, the electrical fuel pump filter was removed and inspected, and there was no evidence of any accumulation of particles or sediment. The gasculator filter was unable to be checked as the gasculator had suffered both impact and fire damage. According to the pilot, during the entire sequence of events, the engine was running smooth, and there was no indication of missing, backfiring, or any fluctuation in rpm. ADDITIONAL DATA AND INFORMATION In a post-accident telephone interview, the pilot said that he did not check the outside air temperature prior to takeoff, nor had he done any takeoff or climb performance calculations. He also stated that he had not calculated the total gross weight of the aircraft, nor figured the center of gravity (CG) location of the aircraft with four people on board. During further conversations with the pilot, it was determined that at the time of the accident the aircraft was carrying approximately 25 gallons of fuel, which is about one-half of its total possible fuel load. Based upon individual passengers weights and an aircraft empty weight of 1,398.22 pounds, the Investigator-In-charge (IIC) calculated the gross weight of the aircraft at takeoff to be 2,258 pounds. This total is 108 pounds over the maximum permissible aircraft gross weight of 2,150 pounds. Based upon the reported 100 degree Fahrenheit (38 degree Celsius) temperature in Cle Elum at the time of the accident, and the Ellensburg barometric pressure of 29.89 inches of mercury, the density altitude at the Cle Elum Municipal Airport's field elevation of 1,945 feet was 5,159 feet. According to the Piper PA-140 owner's handbook, under these ambient conditions the aircraft's maximum gross weight climb performance should be around 460 feet per minute. The handbook does not provide climb performance information for an aircraft loaded above its maximum permissible gross weight.

Probable Cause and Findings

The pilot's failure to obtain and maintain a safe rate of climb after takeoff, due to his failure to perform pre-takeoff weight/balance and takeoff/climb performance calculations. Factors include a high density altitude environment, and trees off the departure end of the runway.

 

Source: NTSB Aviation Accident Database

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