Pontifications engine problems are getting worse – leeham news and comment youtube gas monkey


“The engine lease market will not be able to support the 25-35% increase in shop visit rates forecast for CFM56-7B and -5B engines and continuing strong demand for V2500’s in the period 2019-2024,” IBA wrote. “There is currently very limited availability of spares and unless more spare engines are generated by retirements and aircraft teardowns, or airline held spare stock absorbs some of the demand, IBA expects engine inductions and longer turnaround times (TATs) will create a log jam further intensified by the impact of compound shop visits.”

The engine OEMs have long considered MRO and after-market parts as a profit center. Selling engines, especially in a competitive situation (which is increasingly rare), typically comes at a steep discount. Engines on the Airbus A380 saw discounts of 80%. I know of one case in the MD-11 days in which the winning OEM gave the engines away in exchange for the MRO contract.

The market is in general agreement that despite PW’s current (and excruciating long-running) problems with the GTF, it will eventually be a good engine. The LEAP likewise will be good, but there are some teething problems and its on-wing time initially will be less than the CFM56, an engine that despite the blade issues in 2016 and last month, is a phenomenally durable and reliable engine.

The emergency inspections required by the US FAA and Europe’s EASA on the CFM56 following the Southwest accident illustrates only a fraction of the problems. Here in the Seattle area, there was an unexpected and steady stream of Southwest 737s into Everett’s Paine Field where MRO ATS is located. In just one weekend, there were more than a dozen Southwest airliners on the ground. This picture was repeated throughout the country.

The GEnx icing problems are years old and there’s no end in sight. RR says its Trent 1000 issues won’t be fully resolved until about 2022. PW puts final resolution for the GTF at 2021. There’s no estimate when the TATs for the Trent 700 and GE90 will get back to normal.

According to the excerpts below from the FlightGlobal article at the link after the excerpts, Southwest had completed inspecting 17,000 of its 35,500 CFM56 fan blades prior to the April 17 accident, and was planning to complete inspections of all of them this year, which would have been within the time guidelines of the original CFM service bulletin. After the accident inspections were accelerated to be completed by May 17. With about 10,000 fan blades to go as of 4-26-18, only one cracked blade had been found. Additionally, the blade involved in the accident would not have been covered by the AD that was proposed by the FAA prior to the accident.

“Southwest had been inspecting its CFM56-7B engine fan blades prior to the 17 April accident, following an August 2016 inflight failure of the same engine type on another 737-700 in its fleet. Van de Ven says the carrier had inspected about 17,000 engine blades before last week’s accident, which killed one passenger.

“We were on a path to complete the inspections of the remaining 18,000 by year-end and that would have met the recommended service bulletin timeline,” he adds, referring to a service bulletin issued previously by engine manufacturer CFM International.

The engine involved in the 17 April accident had not yet been inspected as it had accumulated 10,000 cycles since its last overhaul, below the 15,000-cycle threshold for urgent inspections in a proposed US Federal Aviation Administration airworthiness directive. That directive was still in the process of being finalised at the time of the accident last week.

But the accident prompted Southwest to accelerate the inspections, and to complete them within 30 days or by 17 May. Van de Ven says the airline has roughly 35,500 fan blades, which means the airline has about 10,000 fan blades left to inspect at this point.”

Issues with the Leap 1B on the 737MAX have received little attention in the aviation media. But this engine can take really long to start. And it appears to have been a known issue from the outset, as there is an automatic procedure for it. Leap 1A rotor bow issues have been mentioned for the A32xneo but I do not know if they are worse than on the MAX. From the 737 Tecnical site (facebook, not affiliated with Boeing):

“The LEAP-1B engine start sequence is slightly different to the current CFM-56. After the engine start switch is moved to GND, the EEC performs Bowed Rotor Motoring (BRM). This is to straighten the N1 and N2 shafts which may have bowed due to thermal buildup after the previous shutdown. BRM will be active from 6 to 90 seconds and MOTORING will be displayed on the N2 gauge between 18-24%.

At 25% N2 or max motoring when you move the start lever to idle, the EEC then performs a test of the Thrust Control Malfunction Accommodation (TCMA) and Electronic Overspeed System (EOS) functions. This manifests itself as the fuel flow indicating zero, the engine fuel shut off valve opening and closing repeatedly and the ENG VALVE CLOSED light illuminating bright blue until the test has finished whereupon the start sequence continues. It certainly takes longer to start an engine on a MAX than an NG”

Once a Max is pushed from the gate, it can take 5-6 minutes at worst until it is ready to taxi, which is a very long time blocking taxilanes or others from pushing back. I am wondering if this is a long term issue or if there will be anything done to alleviate this in future? Otherwise as the Max fleet grows, this will contribute to additional delays on airports. At least startup times have been MAXimized.

What does it mean when a customer sends you one of their vice presidents to help you clean up your mess? Perhaps they are a really, really helpful customer, or does it instead mean that the customer is seriously upset and doubting your ability to clean up your own mess? After the development of the 787, Boeing certainly has some considerable experience with cleaning up messes, whether of their own making or at vendors. See the excerpts below from the 5-25-18 Bloomberg story at the link after the excerpt.

Keith Leverkuhn is serving as Boeing’s eyes and ears at Rolls factories in Singapore and Derby, England, where the Trent 1000 engine is manufactured and being repaired, said the people. Leverkuhn, an engineer with expertise in propulsion, is best-known for steering Boeing’s 737 Max through development to its commercial debut a year ago, months ahead of schedule.”

“It’s not unusual for aerospace manufacturers to deploy teams of engineers or mechanics to help struggling suppliers to troubleshoot problems. Less common is sending a vice president like Leverkuhn, 57, who is fresh off an assignment to shepherd the upgraded version of the 737, the company’s biggest source of profit.”