Flight Safety Foundation Aviation Mechanics Bulletin 1999

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November–December 1999

Safety Specialists Recommend Precautions for Work in Aircraft Fuel Tanks 16 pages. [PDF 330K]

The fuel tanks of large airplanes are inherently hazardous places to work, full of toxic vapors from jet fuel and associated chemicals that present risks of explosion and chronic illness or death. To minimize the risks, specialists in fuel-tank entry procedures recommend an extensive series of precautions, emphasizing continuous monitoring of the atmosphere inside the tanks to ensure that the level of oxygen is adequate for breathing and that volatile and toxic concentrations of fuel, cleaning solvents and other substances taken into the tanks by maintenance technicians do not exceed legally allowable levels.

September–October 1999

Simultaneous Engine Maintenance Increases Operating Risks 16 pages. [PDF 299K]

Errors committed by the same person or by the same team during maintenance of all engines on a multi-engine aircraft increase the risk of an in-flight total power loss or near-total power loss. Strategies for reducing the risk include a staggered engine-maintenance schedule and redundant checks of completed maintenance.

July–August 1999

Omission of Oil-plug Seals Leads to In-flight Engine Shutdowns 16 pages. [PDF 583K]

The incident inquiry concluded that maintenance error caused oil to be lost from all four engines on a British Aerospace BAe 146. The aircraft, which often is used to transport Britain's royal family, was on a training flight when the incident occurred. The report said that magnetic chip-detector plugs (MCDPs) had been installed without oil seals (O-rings) in all four engines of the BAe 146.

May–June 1999

Managing Aircraft-tire Wear and Damage Requires Adherence to Removal Limits 24 pages. [PDF 1,035K]

Aircraft tire/wheel-assembly failures involve various operational and maintenance factors, but detectable damage to one or more tires sometimes is the underlying cause. Such failures occur infrequently; nevertheless, correctly maintaining tire components — whether in a new tire or a retreaded tire — helps ensure that tire/wheel assemblies will perform reliably under high static loads and dynamic loads. The airframe manufacturer’s procedures typically specify limits for wear and damage.

March–April 1999

Monitoring Aircraft-tire Pressure Helps Prevent Hazardous Failures 24 pages. [PDF 1,220K]

The first lines of defense against catastrophic failures of aircraft tire/wheel assemblies are tire-pressure measurement by maintenance technicians and preflight inspections by flight crews. Despite the increasing reliability and accuracy of pressure-and-temperature sensors and warning systems installed on newer aircraft, such systems provide only safety redundancy and early warning of problems between routine checks.

January–February 1999

Loose Connection on Battery Shunt Involved in Boeing 767 Emergency-landing Incident 20 pages. [PDF 128K]

On May 28, 1996, a Martinair Holland Boeing 767-300ER (B-767) had numerous electrical anomalies as it flew over the North Atlantic Ocean during a scheduled flight from Amsterdam, Netherlands, to Orlando, Florida, U.S. NTSB said, in its Brief of Incident report, that the probable cause of the incident was “numerous electrical anomalies as a result of a loose main-battery-shunt connection and undetermined electrical-system causes.”