321 words but not

ORIGIN

CAUSE

SOURCE

or

WHY

Operating requirements for planes with inoperable instruments and equipment

FAR 121.628 and FAR 135.179

A list of permissible exceptions specific to aircraft model, to the certified configuration of an aircraft.

“The FAR 121.628 is specific about operating with "inoperable" instruments and equipment, but contains nothing about why they might be inoperable.”

“The MEL list is for WHAT equipment is inoperable, not WHY “

MINIMUM EQUIPMENT LISTS

“In most cases malfunctioning units are electrically and mechanically deactivated to prevent unanticipated problems .”

“The system or component must be deactivated before the aircraft can be dispatched…. If the system can’t be deactivated or adequately isolated, the aircraft must be repaired prior to dispatch.”

Some aviation professionals believe…

“MEL does not address the cause only symptoms and 'coping strategies.’”

“I see no hazard in dispatching a plane with a wiring fault provided the problem has been analyzed by a maintenance technician.”

Some aviation professionals believe…

Are they correct?

•Service Difficulty Reports

•NTSB accident/incident reports

•NASA Aviation Safety Reporting System Database

July 3, 2000-Unscheduled B757 landing for smoke, fumes and sparks

LEFT HAND ELECTRIC HYDRAULIC PUMP FAILED. *S/D* CONNECTOR PIN WAS FOUND BURNED FROM ARCING.

Jan 31, 2000-Unscheduled B737 landing for false warning FQIS

GAUGES ERRATIC

REMOVED AND REPLACED LT MAIN FUEL QTY IND DUE TO DAMAGE AND CENTER FUEL QTY IND AS PRECAUTIONARY. CLEARED MEL FOR RT FUEL QTY INDICATION BY REPAIRING WIRE IN RT WING LEADING EDGE FROM BUSSING PLUG.

Low pressure warning light illuminates

B-pump wiring bad

no requirement for pulling circuit breaker

Feb 12, 2002 - B737 Warning indication during flight

Pilot placarding

Means no maintenance oversight for certain MEL items

Local Time: 12:00 PDT

State: CA

City: SAN BERNARDINO

Aircraft Make/Model: DOUG MD-11-11F

Registration Number: N274WA

Operator Name: WORLD

AIRWAYS, INC.

February 22, 1999 deferred maintenance was noted for electric cargo loading system

March 29, in the aft cargo bay floorboards, maintenance noted evidence of a fire

Evidence of wire chaffing and arcing was present on the wire bundle and the frame

where the bundle contacted it. The bundle emanated from the aft cargo loading system

control box.

A metalized Mylar insulation blanket about 2 X 3 feet had burned away, exposing partially burned

insulation material beneath it.

In May, the CAA moved forward

with recommendations

on the MMEL

UK CAA proposed that in addition to considering loss of function, the MMEL assessment should consider the specific effects of failure.

Thai Airways fuel tank explosion

March 2001

“In my opinion electrical problems are not to be taken lightly.Wiring problems are not to be tolerated at all.”

ATSRAC is being asked if the MMELs are implemented appropriately considering what we have learned about wiring

Wiring is a system