Boeing 737 Max investigation after several plane crashes revealed additional concerns with wiring and engines

• Investigations into the Boeing 737 Max planes that were grounded after two deadly crashes have uncovered additional concerns with the wiring and engines.
• The New York Times reports that Boeing's internal audit completed at the request of the Federal Aviation Administration (FAA) found that two bundles of critical wiring might be too close together.
• Previous flaws in the software of the planes could trigger nose dives, and the software fix has yet to be approved in the process of getting the planes back into service that has taken longer than expected.
• The 737 Max engines have also fallen under scrutiny, thanks to a possible weakness in a rotor and a manufacturing problem that left the engines vulnerable to lightning strikes.
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Boeing is still working to ready its 737 Max planes for service again, after two deadly crashes in five months killed 346 people. But the process is taking longer than expected, and investigations have revealed new concerns.

The New York Times reports that Boeing's internal audit completed at the request of the Federal Aviation Administration (FAA) found that two critical bundles of wire that help control the tail of the 737 Max may be too close together, opening the potential for a short circuit. 

Boeing is still working to determine whether a scenario involving a short circuit that could lead to a crash could actually occur. A senior Boeing engineer told the Times anonymously that finding these types of problems and fixing them isn't unusual, and the fix for the wiring would be relatively simple.

The internal audit is intended to determine whether Boeing accurately assessed the dangers of key systems on the planes, given new assumptions on how long it takes pilots and crews to respond to emergencies. 

New software on the planes was partly to blame for the two deadly crashes, which triggered errors that sent the planes into nose dives. Boeing's software fix has yet to be approved, but regulators think the planes could fly by spring. American Airlines and Southwest Airlines have planned commercial Max flights in April.

Investigations into the two crashes found that pilots did not respond as quickly or as effectively as Boeing and the FAA presumed they would when designing and evaluating the software under industry standards. Under new assumptions, if the wiring caused a short circuit that affected the stabilizer, the plane could nose dive.

If the wiring needs to be fixed, Boeing says it would take one to two hours per plane to separate the bundles using a clamp. But changing the wiring could also do additional damage during the repair process, so Boeing is hoping to avoid the possibility.

In addition, the engine manufacturers discovered a possible weakness that could cause a rotor to shatter, and Boeing found a manufacturing problem that caused workers to inadvertently remove panel coating that protects the fuel tank and fuel lines from a lightning strike. 

After Boeing's CEO was fired last month, the interim chief executive and his replacement are contending with a share price that fell 21 percent and tens of billions in charges related to the 737 Max grounding.

However, government officials believe the plane may be cleared for a certification test flight as soon as by the end of January, where Boeing would have to demonstrate the May meets all safety requirements. It would be the regulator's final exam and one of the last steps before the grounding could be lifted.

• Read more:
• Video shows the front wheels of a Boeing 737 collapsing on landing, shooting sparks and terrifying passengers on board
• A Turkish Airlines Boeing 737 crashed off the runway when its front wheels collapsed during a bad weather landing
• The NTSB says Boeing should redesign the engine housing on its 737 jets, which was partly to blame for a deadly Southwest accident
• Boeing's 737 officially lost the title of world's most popular airplane. Airbus' competitor just passed it in sales.

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