Worldwide more than 3,000 CFM International CFM56-7B engines powering Boeing 737-600, -700, -800 and -900 aircraft will have to undergo a series of detailed inspections following an incident on board a Southwest Airlines flight on April 17 that left one passenger dead.
Emergency ADs such as those issued by the FAA and EASA automatically take effect in Australia under the responsibility of the Civil Aviation Safety Authority (CASA).
“This emergency AD was prompted by a recent event in which a Boeing Model 737-700 airplane powered by CFM56-7B model engines experienced an engine failure due to a fractured fan blade, resulting in the engine inlet cowl disintegrating,” the FAA’s AD said.
“Debris penetrated the fuselage causing a loss of pressurisation and prompting an emergency descent.
“Fan blade failure due to cracking, if not addressed, could result in an engine in-flight shutdown (IFSD), uncontained release of debris, damage to the engine, damage to the airplane, and possible airplane decompression.”
The service bulletin called for ultrasonic inspections within the next 20 days on fan blades of engines which have accumulated more than 30,000 cycles.
It also recommended inspections by the end of August for fan blades with 20,000 cycles, and inspections to all other fan blades when they reach 20,000 cycles.
“After first inspection, operators are recommended to repeat the inspection every 3,000 cycles, which typically represents about two years in airline service,” CFM International said in a statement.
The company said there are about 14,000 CFM56-7B engines currently in service with airlines worldwide.
One cycle is a takeoff, landing and full engine shut down.
This service bulletin for inspections within the next 20 days would impact about 680 engines, with about 150 already inspected by operators, CFM International said.
Meanwhile, inspections recommended by the end of August for fan blades with 20,000 cycles would impact an additional 2,500 engines.
“The inspection, conducted on-wing with an ultrasonic probe along the surface of the fan blade, takes about four hours per engine,” CFM said.
“About 60 customers worldwide operate engines within the cyclic thresholds of the new service bulletin.
“CFM partners GE and Safran Aircraft Engines have about 500 technicians directly involved to support customers and minimise operational disruption.”
For Australia’s airlines disruption looks to be minimal
Virgin Australia told Australian Aviation on Monday it had no engines in its Boeing 737 fleet which had accumulated more than 30,000 cycles.
However, there were a small number (understood to be in the single digit range) of engines with individual fan blades that have clocked up more than 30,000 cycles. These individual fan blades would be replaced within 20 days.
No flights have been cancelled or rescheduled as a consequence of these actions.
“Safety is the Virgin Australia Group’s number one priority,” a Virgin Australia spokesperson said in a statement.
“The Group operates Boeing 737-700 and Boeing 737-800 aircraft in its fleet and they are maintained to the highest safety standards, fulfilling all manufacturers’ recommendations and regulatory requirements.
“The Group will fully comply with the directives issued by the Federal Aviation Administration (FAA) and GE Aviation and will conduct the necessary inspections in the mandated time period.
“There will be no impact to customers or to the safety of our operation while these inspections occur.”
At December 31 2017, the airline group had 84 Boeing 737s comprising 82 737-800s and two 737-700s across its Virgin Australia and Tigerair Australia operations, according to the company’s 2017/18 first half results presentation.
Qantas said on Monday it had no engines that had accumulated more than 30,000 cycles, while a small number of engines that have reached 20,000 cycles will be inspected by the end of August as per the ADs.
The airline, which has 75 Boeing 737-800s in its fleet, was not expecting any disruption to its flight schedules as a result of these inspections.
“A small proportion of engines on our Boeing 737-800 fleet currently require further inspections, following the issue of Airworthiness Directives by the FAA and EASA,” a Qantas spokesperson said in a statement.
“These inspections will be completed by our engineers within the required time frame.”
CFM56 “very safe and well-designed”
Thomas Cappelletti, an aviation safety consultant and president of Denver-based Professional Jet Aviation Consultants, said the United States National Transportation Safety Board (NTSB) investigation would seek to determine the factors that led to the fan blade separating from the engine and whether this was an isolated incident.
“The question is, is this a one-off, unique failure over millions and millions of engine cycles,” Cappelletti told Australian Aviation in an interview on Monday.
“Hopefully we will get increased understanding of the potential failure mechanisms in this engine.
“While this latest airworthiness directive is a one-time ultrasonic inspection, I think they will also look more deeply at either tightening the interval between inspections or different types of non-destructive inspections.”
Cappelletti described the CFM engines that power the Boeing 737 fleet as very safe and well-designed.
Flight WN1380
On April 17, Boeing 737-700 N772SW operating Southwest Airlines flight WN1380 from New York LaGuardia to Dallas Love Field suffered an uncontained engine failure about 20 minutes after departure.
Parts of the engine struck the aircraft fuselage, including a window. A 43-year-old mother of two was partially sucked out of the aircraft but remained within the cabin as the 737-700 made an emergency landing at Philadelphia Airport.
The woman was taken to hospital but later died.
VIDEO: Footage of Southwest Airlines Boeing 737-700 after landing at Philadelphia Airport, as shown on the NTSB’s YouTube channel.
Parts of the engine nacelle were found in the ground in Pennsylvania, while a preliminary examination from the NTSB indicated an engine fan blade had broken off and evidence of metal fatigue.
Southwest, one of the United States’ largest domestic carriers and one of the world’s largest operators of Boeing 737 aircraft, suffered a similar occurrence in 2016, when one of the airline’s 737-700s also suffered an uncontained engine failure en route from New Orleans to Orlando.
On that occasion, the flight was diverted to Pensacola and there were no injuries.
Southwest Airlines said in a statement following the April 17 incident it was “accelerating its existing engine inspection program relating to the CFM56 engine family”.
“The accelerated inspections are being performed out of an abundance of caution and are expected to be completed over the next 30 days,” Southwest said.
“The accelerated checks are ultrasonic inspections of fan blades of the CFM56 engines.”
On April 20, the airline later said its existing Southwest Airlines maintenance program met or exceeded “all the requirements specified” in the US FAA’s emergency AD.
Boeing said in a statement on April 17 it had sent a technical team to assist the US NTSB in its investigation.
VIDEO: NTSB chairman Robert Sumwalt’s speaks to the media on April 19 on the Southwest Airlines flight WN1380 incident, as shown on the NTSB’s YouTube channel.
