Narrative:

Upon landing; beta was used to slow the aircraft. The aircraft suddenly yawed to the left very hard due to overspeed of the left engine in beta. The aircraft became uncontrollable and ran off the left side of the runway. The left propeller impacted a runway sign; damaging the sign and the left propeller and engine. Additionally; when the sign came apart; it damaged the leading edge of the left wing; scrapped the underside of the left wing and damaged the outboard left flap. No injuries or other known damage. There was a company employee in the copilot seat and a passenger in the cabin of the aircraft.the right engine had an apparently unauthorized repair to an oil access cap when one of the 4 studs had partially broken. The mechanic had modified the cap by drilling down one of the stud holes in order for the nut to thread onto the remaining portion of the stud. Although this was not a contributing factor to the accident described; the cap should not have been modified to keep the aircraft flying. No leaks were observed from the cap; but the repair was unauthorized as was the ensuing flight. Contributing factors were the need to keep the aircraft and revenue going in a tight economy. New parts were ordered and obtained to make the proper repair.

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Original NASA ASRS Text

Title: During landing a BE-9L pilot selected BETA to help slow the aircraft but the left engine oversped causing the aircraft to exit the runway and strike a runway sign which damaged the left propeller; engine; leading edge and flap. No injuries resulted. Additionally; an unauthorized oil access cap repair had been made which did not contribute to the overspeed.

Narrative: Upon landing; BETA was used to slow the aircraft. The aircraft suddenly yawed to the left very hard due to overspeed of the left engine in beta. The aircraft became uncontrollable and ran off the left side of the runway. The left propeller impacted a runway sign; damaging the sign and the left propeller and engine. Additionally; when the sign came apart; it damaged the leading edge of the left wing; scrapped the underside of the left wing and damaged the outboard left flap. No injuries or other known damage. There was a company employee in the copilot seat and a passenger in the cabin of the aircraft.The right engine had an apparently unauthorized repair to an oil access cap when one of the 4 studs had partially broken. The Mechanic had modified the cap by drilling down one of the stud holes in order for the nut to thread onto the remaining portion of the stud. Although this was not a contributing factor to the accident described; the cap should not have been modified to keep the aircraft flying. No leaks were observed from the cap; but the repair was unauthorized as was the ensuing flight. Contributing factors were the need to keep the aircraft and revenue going in a tight economy. New parts were ordered and obtained to make the proper repair.

Data retrieved from NASA's ASRS site 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.