Enstrom F-28C N51699

Summary

On 20 July 2003 at about 13:30 local time, a Enstrom F-28C registered N51699 was involved in an accident near Waverly, Iowa, 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

20 July 2003 at 13:30

Classification

Accident

Location

Waverly, Iowa, United States

Coordinates

42.7419, -92.5081

Aircraft

Enstrom F-28C

Registration

N51699

Category

Helicopter

Engines

1

Operator

Not recorded

Operating rule

Part 91: General Aviation

Purpose of flight

Aerial Observation

Phase of flight

Not recorded

Route

Waverly → Unknown

Aircraft damage

Substantial

Weather

VMC

Light

Day

NTSB number

CHI03LA217

Nobody was injured.

The main rotor blade push-pull rods being corroded, sustaining fatigue, and separating in cruise and the main rotor blade contacting the tail boom during the emergency landing. Factors were the diminished aircraft control and the vibrations encountered during flight after the rod separation.

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

Read the full NTSB narrative

The helicopter sustained substantial damage when the main rotor blade impacted the tail boom during a forced landing. The helicopter experienced in-flight vibrations prior to the forced landing. The pilot stated that the helicopter experienced extreme vibration in-flight at 200 feet above ground level. He said that helicopter control was "10% to nil." An examination revealed that one of three Push-Pull Rod Assemblies, part number 28-16253-1, was found corroded and separated. The operator's fleet of aircraft was examined and four other control rods were found with corrosion. Examination of the rod with the separation from the accident helicopter at the National Transportation Safety Board's Materials Laboratory revealed that "most of the fracture areas were on a plane that was nearly perpendicular to the longitudinal axis of the rod, indicative of a brittle fracture mechanism such as fatigue cracking." The pilot stated, "Pitch control rod has no inspection procedure at this time. It rusted from inside and not visible from outside." Subsequent to the accident, Enstrom issued Service Directive Bulletin (SDB) No. 0096. The bulletin directs visual inspection of control rods with part number 28-16253-1 and 28-16253-101 according to their time in service on F-28A, F-28C, F-28F, 280, 280C, 280F, and 280FX helicopters.

Quoted verbatim from the NTSB record.