Robinson R44 N402PD

Summary

On 5 April 2008 at about 05:03 local time, a Robinson R44 registered N402PD, operated by Topeka Police Department, was involved in an accident near Topeka, Kansas, United States. 3 people were on board and nobody was injured. The aircraft was substantially damaged. The NTSB has published a probable cause for this accident; it is quoted in full below.

Date

5 April 2008 at 05:03

Classification

Accident

Location

Topeka, Kansas, United States

Coordinates

39.0692, -95.6208

Aircraft

Robinson R44

Registration

N402PD

Category

Helicopter

Engines

1

Operator

Topeka Police Department

Operating rule

Part 91: General Aviation

Phase of flight

Not recorded

Route

Topeka → Topeka

Aircraft damage

Substantial

Weather

VMC

Light

Night

NTSB number

DFW08TA092

Nobody was injured.

A malfunctioning magneto, resulting in a high engine rpm and low rotor warning indications. A contributing factor was the impact with a light pole, during the precautionary landing.

Quoted verbatim from the NTSB record. This site does not paraphrase or interpret it.

Read the full NTSB narrative

During a routine night surveillance flight, the helicopter's pilot heard the single reciprocating engine "fluctuate" slightly; he noted that the engine's rpm gauge was above the "normal operating limits", and the gauge [needle] was "jumping up-and-down". In order to keep the engine within operating limits, the pilot disabled the engine governor and decreased the engine rpm. During the return to base, the pilot heard the engine rev up and the low rotor rpm alarm. During the precautionary landing in a parking lot, the helicopter's main rotor blade contacted a light pole. The helicopter subsequently made a hard landing, coming to rest on its side. The magneto, governor controller, clutch actuator, engine/rotor tachometer and drive-belts were removed for examination. The governor, clutch actuator, tachometer, and drive belts all passed either a visual or electronic test inspection. A visual inspection of the magneto revealed that the exterior of the magneto was absent any damage, but was lightly covered with an "oil like" liquid. The magneto was bench tested and produced regular sparks beginning at 196 rpm's. The magneto’s signals to the governor box were clear and equal, with only a very slight overlap between both signals. The magneto was disassembled; the light oil like substance was present on the inside of the magneto. The inspection also revealed "whiskers" of residue/corrosion on the magneto contacts; which were black instead of the normal silver color. During the test it was noted that the magneto should have produced a regular spark at 150 rpm, and that the residue/corrosion could send extra impulse signals to the governor box; producing an indication that the engine is revving. However, it was also noted that because there was only a slight overlap of the electrical signals, and since the magneto passed the other test items,a malfunction could not be duplicated.

Quoted verbatim from the NTSB record.