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NTSB Identification: IAD99WA033
On March 2, 1999, approximately 1825 local (Portugal) time, a Robinson R-44, registration CS-HEI, serial no. 0448, owned and operated by Heliportugal, and contracted for electronic news gathering by a national television news station, sustained substantial damage following a loss of engine power and autorotation. Daylight and visual meteorological conditions prevailed at the time of the accident. The commercially certificated pilot and the passenger were not injured. The flight was conducted under Portuguese CAA rules.

The pilot was flying the helicopter en route to the Heliportugal operations base at Casias Municipal Airport, following work in television news-gathering. At 1,300 feet mean sea level, in the vicinity of Sines, Portugal, the helicopter passed within 1,000 meters of the main lobe of a high frequency (HF), high energy broadcasting transmission antenna. The pilot reported that he suddenly noted strong interference in the intercommunications system and on the communication and navigation radios, followed by illumination of the low rotor RPM and clutch lights. He further noted that the engine noise dropped to idle level, and the engine and rotor RPM indications dropped. He lowered the collective immediately to maintain rotor RPM and entered into an autorotation. During the descent he adjusted the collective to keep the rotor RPM indication in the green arc. At approximately 200 feet, the engine responded to throttle input, and the engine accelerated rapidly, resulting in the engine and rotor RPM exceeding the upper limitations. The pilot landed successfully and there were no injuries. After landing, he noted that the lower rotor RPM and clutch lights were extinguished, and cockpit indications were normal. He then lifted off and flew the helicopter to base.

Visual examination found severe damage to the main rotor blades, which were removed and replaced. Examination found no electronic systems damage or other damage to the helicopter. The engine governor was removed and sent for laboratory examination relative to suspected severe electromagnetic and radio interference impinging upon engine and related systems.

The helicopter had 89:40 total flight hours at the time of the accident. Records showed that the next, 100 hour inspection, was due at 105:15 total hours.

The pilot had a total of 2,098 helicopter flight hours, including 30 hours in the R-44.

For further information, contact: Investigator-in-Charge, Frederico J. F. Serras, tel. 351-1-8423500, fax. -581, Lisbon. NTSB: U.S. Accredited Representative, Thomas R. Conroy, (202) 314-6314, Washington, D.C.; Engineering Investigator, Scott Warren