Narrative:

I flew a robinson R44 on a part 91 personal flight from the helicopter pad with two passengers. Weather on the date of the flight included a local altimeter setting of 29.96; density altitude of 1;800 ft and light winds out of the southeast. During run-up; the helicopter's OAT gauge read 95 degrees fahrenheit on the concrete helipad; and approximately 89 degrees over the grass. Nearby flags indicated winds directly out of the east at approximately 8-12 mph. The helicopter's total weight on the incident flight was approximately 2;175 pounds. The R44's gross weight is 2;400 pounds. At the given weight and temperature; the R44 has a demonstrated ability to maintain a zero wind oge (out of ground effect) hover at approximately 3;000 ft AGL. In other words; the helicopter was operated well inside its published operating envelope. I performed a normal run up and all checklist items appeared normal. Upon takeoff; the helicopter developed insufficient climb power. I dropped off a passenger; and thinking the helicopter would now climb easily; entered a second maximum performance takeoff. The helicopter again developed insufficient power; but the engine did not miss; surge; backfire; or give any other indication of partial lack of power. Seconds into the flight; rotor RPM decayed and I entered an autorotation and made an emergency landing in a private front yard; having narrowly missed several houses and other obstacles.after the remaining passenger departed; the engine suddenly surged; then appeared to behave normally. As bystanders approached the aircraft from all directions; including the direction of the tail rotor; and fearing for their safety; I made the immediate decision to takeoff again. The helicopter performed perfectly on each subsequent flight. The cause of the loss of power has not yet been determined.

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Original NASA ASRS Text

Title: While apparently within temperature and gross weight limits; an R44 pilot experienced diminished engine power on liftoff. After removing one passenger; helicopter again developed insufficient power and pilot made an emergency landing in a private yard. On a subsequent takeoff with no passengers; the engine developed full power.

Narrative: I flew a Robinson R44 on a Part 91 personal flight from the helicopter pad with two passengers. Weather on the date of the flight included a local altimeter setting of 29.96; density altitude of 1;800 FT and light winds out of the southeast. During run-up; the helicopter's OAT gauge read 95 degrees Fahrenheit on the concrete helipad; and approximately 89 degrees over the grass. Nearby flags indicated winds directly out of the east at approximately 8-12 MPH. The helicopter's total weight on the incident flight was approximately 2;175 LBS. The R44's gross weight is 2;400 LBS. At the given weight and temperature; the R44 has a demonstrated ability to maintain a zero wind OGE (Out of Ground Effect) hover at approximately 3;000 FT AGL. In other words; the helicopter was operated well inside its published operating envelope. I performed a normal run up and all checklist items appeared normal. Upon takeoff; the helicopter developed insufficient climb power. I dropped off a passenger; and thinking the helicopter would now climb easily; entered a second maximum performance takeoff. The helicopter again developed insufficient power; but the engine did not miss; surge; backfire; or give any other indication of partial lack of power. Seconds into the flight; rotor RPM decayed and I entered an autorotation and made an emergency landing in a private front yard; having narrowly missed several houses and other obstacles.After the remaining passenger departed; the engine suddenly surged; then appeared to behave normally. As bystanders approached the aircraft from all directions; including the direction of the tail rotor; and fearing for their safety; I made the immediate decision to takeoff again. The helicopter performed perfectly on each subsequent flight. The cause of the loss of power has not yet been determined.

Data retrieved from NASA's ASRS site as of July 2013 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.