Flight Safety Foundation Aviation Mechanics Bulletin 1997

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November–December 1997

FAA Airworthiness Directives Focus on Ignition Sources Boeing 747 Fuel Tanks 32 pages. [PDF 817K]

The U.S. Federal Aviation Administration (FAA) has issued one Airworthiness Directive (AD) and one Notice of Proposed Rulemaking (NPRM) — a proposed AD — applicable to many Boeing 747 series airplanes to reduce the possibility of fire and explosion caused by potential ignition sources in or near fuel tanks. The AD and NPRM were prompted by the investigation following the Trans World Airlines (TWA) Flight 800 accident.

September–October 1997

Inflight Engine Fire Caused by Uncapped Fuel Drain, Prompts NTSB Safety Recommendations 20 pages. [PDF 269K]

A recent in-flight engine fire involving a twin-turboprop illustrates that diagnosing and correcting a mechanical problem is only the first step in preventing the accident from recurring. The second, and equally important, step is following the proper notification procedures so that personnel can be alerted about accident-causing problems.

July–August 1997

Knowledge of Hazardous Chemicals in the Aviation Workplace Can Help Prevent Work-related Illness and Injury 28 pages. [PDF 387K]

Aviation maintenance facilities use a number of substances containing chemicals that regulatory agencies have labeled as toxic. These include solvents, cleaning agents, hydraulic fluids, coolants and fuels. Inappropriate exposure to or ingestion of toxic substances may lead to illness or injury, ranging from short-term effects such as headache, shortness of breath and dizziness, to paralysis, kidney failure, cardiovascular disease, blindness, respiratory ailments and even death.

May–June 1997

Fatigue Crack Leads to MD-83 Left Main Landing Gear Collapse on Rollout 20 pages. [PDF 862K]

The U.K. Air Accidents Investigation Branch (AAIB) found that the cause of the accident was the failure of the forged landing-gear oleo (hydraulic) cylinder at a point just below its attachment trunnions; that the cylinder failure resulted from a visually undetectable fatigue crack in its forward face; and that the crack began with multiple small fatigue origins associated with grit-blasting during manufacture, but had been exacerbated over time by self-sustaining vibrations of the MLG.

March–April 1997

FAA Proposes Airworthiness Directives for Modifying Boeing 737 Rudder Control Systems 20 pages. [PDF 208K]

The U.S. Federal Aviation Administration (FAA) has proposed two airworthiness directives (ADs) that would require modifications to the rudder control system of all operational Boeing 737 aircraft. Both proposed Ads are intended to reduce the risk of inadvertent rudder movements.

January–February 1997

FAA Airworthiness Directive Requires Inspection of Wiring and Conduits to Boeing 747 Fuel Pumps 16 pages. [PDF 191K]

The U.S. Federal Aviation Administration (FAA) has issued an airworthiness directive (AD), applicable to many Boeing 747 models, to reduce the possibility of frayed wiring causing electrical arcing that could lead to fire or explosion in a fuel tank. The AD announcement described the rule as “an emergency regulation that must be issued immediately to correct an unsafe condition in aircraft … .”