Beechcraft BH 125-600A N454DP

Summary

On 18 August 1999 at about 01:17 local time, a Beechcraft BH 125-600A registered N454DP was involved in an accident near Las Vegas, Nevada, United States. 8 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

18 August 1999 at 01:17

Classification

Accident

Location

Las Vegas, Nevada, United States

Nearest airport

McCarran International (LAS)

Coordinates

Not recorded

Aircraft

Beechcraft BH 125-600A

Registration

N454DP

Category

Airplane

Engines

2

Operator

Not recorded

Operating rule

Part 91: General Aviation

Purpose of flight

Executive/Corporate

Phase of flight

Not recorded

Route

Salina → Unknown

Aircraft damage

Substantial

Weather

VMC

Light

Day

NTSB number

LAX99FA272

Nobody was injured.

the complete failure of all hydraulic systems due to the effects of a main gear tire disintegration on takeoff. Also causal was the manufacturer's inadequate design of the wheel wells, which did not comply with applicable certification regulations, and the FAA's failure to ensure that the airplane's design complied with standards mandated in certification regulations.

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

Read the full NTSB narrative

The pilot landed with the landing gear in the retracted position, when both the main and auxiliary hydraulic systems failed to extend the gear. The airplane caught fire as it skidded down the runway. The left inboard main tire had blown on takeoff and a 30-inch section of tread was loose. Black marks were along the length of the landing gear strut and up into the wheel well directly above the left inboard wheel. The normal and emergency hydraulic systems both connect to a common valve body on the landing gear actuator. This valve body also had black marks on it. A gap of 0.035 inch was measured between the valve body and actuator. When either the normal or auxiliary hydraulic system was pressurized, red fluid leaked from this gap. Examination revealed that one of two bolts holding the hydraulic control valve in place had fractured and separated. The fractured bolt experienced a shear load that was oriented along the longitudinal axis of the actuator in a plane consistent with impact forces from the flapping tire tread section.. Separation of only one bolt allowed the control valve to twist about the remaining bolt in response to the load along the actuator's longitudinal axis. This led to a loss of clamping force on that side of the actuator. Hydraulic line pressure lifted the control valve, which resulted in rupture of an o-ring that sealed the hydraulic fluid passage. 14 CFR 25.739 describes the requirement for protection of equipment in wheel wheels from the effects of tire debris. The revision of this regulation in effect at the time the airplane's type design was approved by the FAA requires that equipment and systems essential to safe operation of the airplane that is located in wheel wells must be protected by shields or other means from the damaging effects of a loose tire tread, unless it is shown that a loose tire tread cannot cause damage. Examination of the airplane and the FAA approved production drawings disclosed that no shields were installed to protect the hydraulic system components in the wheel well.

Quoted verbatim from the NTSB record.