Boeing 737 Max engine issue can cause smoke in the Cabin, warns NTSB

Boeing 737 Max: US safety investigators have called for urgent action regarding an engine issue on the Boeing Co. 737 Max aircraft that could fill the cockpit and cabin with smoke.

The National Transportation Safety Board’s recommendation comes after two such incidents were reported in which planes were filled with smoke after large birds struck their engines.

Safety feature malfunction caused the smoke

Both incidents involved 737 Max aircraft flown by Southwest Airlines and powered by Leap-1B engines made by CFM International, which is a joint venture of GE Aerospace and Safran SA. The NTSB connected the incidents to a malfunction with one of the engine’s key safety features.

In both cases, damage to the fan blades following the bird strikes activated a safety feature known as the load reduction device in the Leap-1B engines. This device is meant to protect the aircraft from heavy vibrations that can cause further problems. However, in those incidents when the system activated, there was a malfunction that led to oil leaking into the hot section of the engine, causing smoke to enter the cockpit or cabin and posing a potential safety risk.

Safety agency alerts crews at risk

The safety agency on Wednesday urged the Federal Aviation Administration to ensure flight crews are alerted to the problem and to emphasise revisions Boeing has made to flight manuals detailing steps pilots should take if they come across any issues, Bloomberg reported.

It also asked the FAA, as well as other aviation authorities in the European Union and China, to determine whether the same issue exists in other variants of the Leap engine used by Airbus SE and Commercial Aircraft Corp. of China Ltd., known more commonly as Comac.

The FAA said that both the regulator and Boeing have alerted operators to the issue. “We advised operators to evaluate their procedures and crew training to ensure they address this potential issue”. “When the engine manufacturer develops a permanent mitigation, we will require operators to implement it within an appropriate timeframe,” the news agency reported.

Work is underway to fix the issue

A spokesperson for CFM said that work is already underway to address the smoke risk. This includes a software update for the Leap-1B and assessments to determine whether other variants have a similar issue.

According to Bloomberg, Boeing also responded by stating that it has been working with CFM on the software update and supports the NTSB’s recommendation.

“We’re reviewing the recommendations and have mitigation procedures currently in place,” Southwest said in a statement. The carrier said it is in close contact with the FAA, Boeing and CFM on the issue and on identifying a permanent solution. Southwest also said it notified its flight crews about the potential effects of some bird strikes following the incidents, which both occurred in 2023.

Recommendations to fix the issue

The NTSB announced in November that it was investigating one of the 2023 occurrences.

Bloomberg said that decision came after the FAA said it would hold a Corrective Action Review Board to evaluate internal recommendations compiled by a small group of the regulator’s investigators that had leaked to the public.

The recommendations included a short-term fix that would require pilots to temporarily alter takeoff procedures while Boeing worked on a more permanent solution.

However, the FAA’s Aircraft Certification Service determined that the short-term change wasn’t necessary and instead proposed mandating a longer-term fix to update the engine software, according to a memo from the Transportation Department’s Office of Inspector General, the new agency reported.