NAS Whidbey, WA, USA
N25455
Cessna 152
Although the pilot of the Cessna 152, who had been cleared by the tower to taxi into position and hold for takeoff, was aware that the large military turboprop aircraft he had to taxi behind may be doing periodic engine runs, he did not initiate communications that would positively ascertain the power settings of its engines. Just about the time he attempted to taxi past, two of the turboprop's four engines were advanced to a high power setting, and the resultant propwash flipped the 152 on its back. The crew of the turboprop aircraft, who were monitoring ground, were not aware that an aircraft was taxiing behind them after being cleared by the tower to taxi into takeoff position and hold.
On March 17, 2002, at 1749 Pacific standard time, a Cessna 152, N25455, was blown over by the propwash of another aircraft while taxiing for takeoff at Naval Air Station (NAS) Whidbey Island, Oak Harbor, Washington. The certified flight instructor and his student received minor injuries, and the aircraft, which is owned by the United States Navy, and operated by the NAS Whidbey Island Flying Club, sustained substantial damage. The 14 CFR Part 91 local instructional flight was taxiing for takeoff in visual meteorological conditions at the time of the accident. No flight plan had been filed. There was no report of an ELT activation. According to the instructor, after completing the pre-takeoff engine run-up check in the run-up area southwest of runway 07-25, a request was made for a departure from runway 31. Because a Navy EA6B Prowler was also ready for departure on runway 31, Whidbey Tower asked N25455 if they could accept a departure on runway 25 instead. The instructor in N25445 responded that he was "... reluctant to take a two five long with that P-3 turning there." The tower therefore instructed N25455 to "hold short." Approximately 90 seconds later, after the EA6B on runway 31 had initiated its takeoff roll, the tower asked N25455 if they wanted "...Bravo North now?" Although taxi to a takeoff from Bravo North (Bravo North is a taxiway between the approach ends of runways 07 and 13 that is approved for takeoff and landing for the NAS Whidbey Island Flying Club aircraft) would require passing behind the P-3 turning engines in the run-up area northwest of the approach end of runway 07, N25455 responded with "Sure, we can take Bravo North." Whidbey Tower then immediately told N25455 "If you would like 31, you can have it." But the response to that offer was "Four Four Five, we will take Bravo North." At that point the tower cleared N25445 to taxi into position and hold for departure at Bravo North. Although N25445's taxi behind the left wing of the P-3 was uneventful, as it was passing behind the right wing, it encountered a high-power propwash that lifted its tail and flipped it on its back. In a post-accident telephone interview with the NTSB, the instructor in N25445 said that he knew the P-3 was doing some kind of periodic engine runs, and that it had been in that location when he landed on runway 31 and taxied near it on his previous instructional flight that day. He further stated that he had elected not to depart on runway 25 because he was concerned that the aircraft may encounter propwash from the P-3 during rotation or just after takeoff. He also said that the reason he felt it was safe to taxi behind the P-3 was because he had seen a Cherokee taxi behind it during the time his student was doing the pre-takeoff engine run-up, and because he checked the windsock located behind the P-3 just prior to initiating the taxi. He also tried to taxi as far to the east as he could in an attempt to maximize the distance between N25445 and the P-3, "... just in case there was any propwash, we could avoid any that was present." When asked if he had attempted to ascertain through Tower or Ground Control the status of the P-3's engine power settings, he said that he had not. Since the pilot did not seek this information, and because neither FAA Order 7110.65N (Air Traffic Control) nor the NAS Whidbey Island Air Operations Manual require the tower to keep the pilot advised of the current power setting of the turning aircraft, he had no way to know that the power was being increased just as he attempted to pass behind the subject aircraft. According to the crew that was doing the engine trim/test runs in the P-3, they had been monitoring Ground Control and were not aware that Tower had cleared an aircraft into position to hold for takeoff on taxiway Bravo, or that an aircraft was taxiing behind them. At the time they were notified by Ground Control that an aircraft had flipped over behind them, they had just moved the power levers on two engines (#1 and #4) to a 4,300 shaft horsepower setting.
The pilot's improper decision to taxi behind a standing large military turbo-prop aircraft, which he knew may be performing periodic engine test runs, without first initiating communications to insure that the engine power on the standing aircraft would remain at idle as his aircraft taxied passed, thus leading to an inadvertent encounter with high-power propwash.
Source: NTSB Aviation Accident Database
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