Boeing 737 Safety Record

the improper installation of the fuselage crown skin panel at the S-4L lap joint during the manufacturing process, which resulted in multiple site damage fatigue cracking and eventual failure of the lower skin panel. Contributing to the injuries was flight attendant A's incorrect assessment of his time of useful consciousness, which led to his failure to follow procedures requiring immediate donning of an oxygen mask when cabin pressure is lost.

An uncommanded elevator surface deflection as a result of a left elevator PCU input arm assembly jam due to FOD lodged between the input arm assembly and the PCU housing. The FOD was a roller element from an elevator upper torque tube output crank bearing, but how or when the roller element liberated from its bearing assembly could not be determined. Contributing to the survivability of this incident was the flight crew’s immediate actions in response to the elevator control system jam.

The pilot's inadvertent application of excessive braking after touchdown, which caused the right wheels to lock and several tires to blow and resulted in a subsequent brake fire.

The placement of operating equipment in close proximity to an external heating unit's intake by ground personnel, resulting in the contamination of the airplane's cabin with carbon monoxide.

An inadvertent encounter with severe turbulence during descent and the failure of two passenger seat belt attach fittings. Contributing to the incident was the failure of the operator to comply with the SAIB.

A short circuit in the primary (non-rechargeable) battery, most likely due to it being recharged. This internal short led to thermal runaway, battery failure, and an explosion.

The airplane tug driver's inadvertent movement of the tug gear shift lever from forward to reverse, which resulted in the nose landing gear collapse. Contributing to the accident was the defective gear shift lever.

the snowplow driver's failure to see the airplane during plowing operations. Factors contributing to the accident were the snowplow driver's excessive speed and the snow.

The second in command failed to maintain proper runway alignment, directional control, and landed long. The pilot in command failed to execute a go-around and failed to provide adequate supervision. Additional factors included the thunderstorm, the dark night, the muddy terrain, and the FODed engines.

(1) the capping of the incorrect hydraulic line by mechanics, which led to the failure of hydraulic system A; (2) the mechanics' lack of experience working with the Boeing 737 hydraulic system; and (3) the maintenance controller's failure to ascertain more information regarding the leaking hydraulic line before instructing the mechanics to cap the line and deactivate the right thrust reverser. Contributing to the cause of the accident were (1) the asymmetric directional control resulting from the deactivation of the right thrust reverser; (2) the depletion of the left and right inboard brake accumulator pressure because of the flight crew's use of the rudder pedals with only the left thrust reverser to control the direction of the airplane down the runway; (3) the failure of the right outboard brake because the airplane was slowed without the use of the left and right inboard brakes and was traveling at a higher-than-normal speed and with heavy gross weight; (4) the failure of the right outboard brake after one of the right outboard pistons overtraveled and unported its o-ring, allowing system B hydraulic fluid to deplete and the left outboard brake to fail; and (5) the mechanics' improper use of the illustrated parts catalog for maintenance and troubleshooting and the maintenance controller's failure to use the appropriate documents for maintenance and troubleshooting.

Inadequate visual lookout by ground personnel (tug operator). Factors include failure of the airline to provide proper assistance (wing walkers) to the tug operator, and inadequate pushback procedures by the airline; inattention of the catering truck driver, and failure of the flight crew to illuminate the rotating beacon prior to or during pushback.

The captain's failure to maintain directional control during landing roll. Factors were the loss of hydraulic pressure in the 'A' hydraulic system, the thrust reverser failure on the number one engine, and flight crew coordination not being maintained.

inadequate nickel plating was applied to the compressor disk during the rework process at the operator's overhaul facility, which resulted in a brittle fracture in the disk and an uncontained engine failure. A factor was the operator's lack of written procedures and guidance for personnel on the NiCad plating line, along with their failure to supply a method of measuring the thickness of nickel applied.

a laser light source of undetermined origin, directed by unknown person(s) toward the cockpit window of the aircraft, while the aircraft was on an approach to land.

The flying pilot's inadvertent exposure to an unidentified ground-based laser beam. A factor in the incident is the lack of appropriate standards by the FAA and FDA for laser light exposure levels to aircrew in navigable airspace.

INADEQUATE WRITTEN MAINTENANCE PROCEDURES ADDRESSING STEPS TO BE FOLLOWED IN THE EVENT OF A COMPONENT FAILURE DURING AN ENGINE WASH. THE EMERGENCY SLIDES FAILED TO DEPLOY DUE TO IMPROPER INSTALLATION BY COMPANY MAINTENANCE PERSONNEL.