MKS

ntsb wants older 747s checked and rewired

by:MKS     2020-03-02
WASHINGTON (CNN)--
On Tuesday, the National Transportation Safety Board recommended mandatory inspections and rewiring of the tanks of hundreds of old Boeing 747 aircraft to deal with the debris found on TWA 800 and other aircraft. In a 10-
NTSB chairman Jim Hall to the Federal Aviation Administration director Jane Garvey\'s peichita letter asked the FAA to request wiring and fuel probe checks on the three early series of large jets-the 747-100, 747-200 and 747-300.
The museum also suggested that other types of aircraft fuel meter systems are similar to those of the old 747, including Boeing 707s and C-
130 military transport aircraft.
Hall said the NTSB found that the wires were damaged in the TWA 800 and some other old 747 oil meter systems, including three already retired wires.
Without blaming the TWA accident on any particular source, Hall wrote, \"unsafe conditions. . .
May exist in other old B-
747, shall be handled by the Federal Aviation Administration.
\"On July 1996, TWA 800 crashed into the sea near New York, killing all 230 people on board after an explosion ripped the plane apart.
For months, security investigators have been trying to find a power source that lights smoke in the aircraft\'s central fuel tank.
NTSB said: On the whole, these suggestions mean that all the 750 olderBoeing 747 that are still in use will have to be checked and may be re-routed on a large scale.
The rest of the proposals may affect 500 to 600 new 747-
And other types of aircraft. -
Because NTSB wants them to apply to \"all applicable transport aircraft fuel tanks \".
\"The safety committee recognizes the difficulties and costs associated with physical separation (fuel-monitoring)
Wires from other wires and in-
\"The plane that serves the airline,\" Hall wrote . \".
\"Separated, however. . . (fuel-
Monitoring wires)
By shielding and separating from other power sources, the fuel tank wires can be protected from the power supply that could ignite the explosive steam in the fuel tank.
Rewiring will be a huge and expensive job, industry insiders say.
Most of the issues mentioned in the letter were discussed at a hearing in Baltimore on December, and the FAA and Boeing are already dealing with them.
But Hall\'s letter appears to be intended for more action by Boeing and the FAA.
Hall, for example, acknowledged that the upcoming Boeing Service announcement would involve a more comprehensive inspection of the oil meter wiring, but noted that such an announcement was not mandatory.
Only the FAA has the authority to authorize these changes, and it issued a statement on Tuesday expressing its intention to agree with the NTSB proposal.
But it sharply reminded the board that it had kept the board informed of the actions that had been taken.
\"The FAA is actively working with NTSB and Boeing to develop short-termand long-
Long-term solutions to fuel problems
Tank ignition source and reduction or elimination of explosive fuel-
\"The air mixture,\" the statement said.
FAA officials said that in the actions already taken, they had ordered the replacement of the terminal blocks that could cause the oil gauge wiring to wear out.
In a brief statement, Boeing said it was working on a series of fuel system service announcements that it believed would address the NTSB\'s proposal.
The main suspect of the TWA disaster is a combination of events involving damaged wires and fuel corrosion
A measuring rod that may introduce a spark or flame into the central fuel tank.
Tanks are almost empty, and the steam inside will heat up when the plane sits on the runway on a hot day waiting to take off.
At last year\'s NTSB hearing, Boeing experts testified that the company has been testing different methods to protect the central tank from explosions ---
Includes the use of different types of fuel.
Hall\'s letter said the NTSB also found two \"inappropriate repairs\" in the fuel\"
Monitoring wire for TWA 800 wing-
Although investigators do not believe they contributed to the accident, they tip the tank.
TWA issued a statement saying the repairs were carried out in accordance with Boeing and FAA procedures.
Journalists Christine Negroni and Reuters contributed to the report.
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