Cessna 172M N73115

Summary

On 25 July 2012 at about 18:20 local time, a Cessna 172M registered N73115 was involved in an accident near San Juan, United States. One person was on board and one died. The aircraft was substantially damaged. The NTSB has published a probable cause for this accident; it is quoted in full below.

Date

25 July 2012 at 18:20

Classification

Accident

Location

San Juan, United States

Nearest airport

Fernando Luis Ribas Dominicci (TJIG)

Coordinates

18.4553, -66.1047

Aircraft

Cessna 172M

Registration

N73115

Category

Airplane

Year built

1976

Engines

1

Operator

Not recorded

Operating rule

Part 91: General Aviation

Purpose of flight

Personal

Phase of flight

Not recorded

Route

Arecibo → San Juan

Aircraft damage

Substantial

Weather

VMC

Light

Day

NTSB number

ERA12FA484

1 person died.

Maintenance personnel’s improper lubrication of the right direct aileron control cable and failure to detect the severe corrosion of the cable during a maintenance inspection, which resulted in the in-flight failure of the cable, the pilot’s subsequent inability to maintain aircraft control, and the airplane’s impact with terrain.

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

Read the full NTSB narrative

About 4 minutes before the accident, the pilot advised an air traffic controller that an aileron cable had broken but that he was continuing to the airport to land. Security video and eyewitness reports revealed that the airplane was at low altitude and appeared to be maintaining level flight until it banked right, descended, and impacted water near the airport in a right-wing-down attitude. A postaccident examination of the wreckage indicated that all of the airplane's flight control cables were lubricated except for a fractured section of aileron control direct cable near the doorpost pulley, which was likely not properly lubricated. Most of the cable strands and the doorpost pulley and bearing exhibited severe corrosion near the fracture. When manipulated by hand, the pulley bearing would not rotate due to the corrosion. Analysis of the cable, doorpost pulley, and an exemplar cable from a similar make and model aircraft that had been flown in similar atmospheric conditions (in what is considered a severe corrosion zone) revealed moderate to severe corrosion. It is likely that, during the airplane's maintenance inspection 6 months before the accident, the mechanic failed to detect the corroded cable due to the difficulty in visually seeing the cable. It is also likely that the doorpost pulley's failure to rotate resulted in tension on the right aileron control cable, which subsequently caused it to fail due to the severe corrosion. The aircraft manufacturer's maintenance manual for the airplane gives specific instructions for lubricating and inspecting flight control cables and pulleys every 600 hours or 12 months, whichever comes first, including, in part, examining the cables for corrosion and the pulleys to ensure smooth rotation. After the accident, the manufacturer produced a video emphasizing the importance of properly examining and lubricating the cables.

Quoted verbatim from the NTSB record.