Boeing prepares to swap engines from MAX inventory to new production planes

Boeing had 290 737 MAXs in storage as of June 30, leftovers from the 2019 grounding. Now that inventory can be the source of engines for new production planes.

Planning is underway to draw engines from the large inventory of stored 737 MAX aircraft for installation on new production planes, Leeham News confirmed.

Boeing Co. (NYSE: BA)

With regard to the supply chain, we continue to encounter real constraints. We are taking steps to mitigate risk in a number of areas, including engines.

— David Calhoun, CEO of Boeing Co.

BAINBRIDGE ISLAND, WA, USA, Aug. 15, 2022 / — © Leeham News: Boeing CEO David Calhoun says the company will not build 737 gliders. This is what planes are called when they come out of final assembly without engines. The mitigation, to use Calhoun’s word, ironically comes from a circumstance that has plagued Boeing since March 2019.

Planning is underway to draw engines from the large inventory of stored 737 MAX aircraft for installation on new production planes, LNA confirmed.

Boeing produces 20 to 30 sets of counterweights for ships, according to LNA. The counterweights are yellow blocks suspended from the pylons to which the engines are attached. The weights are needed to keep the planes from sitting on their tails without the heavy engines installed. The counterweights will be installed on aircraft in storage when the CFM LEAP-1B engines are retired for installation on new production aircraft as they roll off the final assembly line in Renton, WA.

Inventory gives flexibility

There were 290 MAXs in stock at the end of the second quarter on June 30. This figure includes an unidentified number of new production aircraft awaiting delivery, but which are counted as inventory. There are around 140 aircraft built for Chinese airlines. The large inventory gives Boeing the flexibility to make deliveries when it needs them, a source with direct knowledge of the situation told LNA.

Swapping engines before delivery is not uncommon. Boeing and Airbus have done this in the past. When Airbus was faced with producing dozens of gliders at the start of the neo program, engine swaps were not uncommon. During the period when Pratt & Whitney’s GTFs were being removed from in-service aircraft at high rates as parts worn out or failed prematurely, Airbus swapped engines for new production aircraft to service their customers. At one time, Airbus had over 100 neos stored in Toulouse and Hamburg without engines.

white tails

When the MAX grounded, 450 aircraft were built before production was suspended. These went into storage at Boeing’s facilities in Renton (WA), where the assembly line is located; at Boeing Field in Seattle, where the delivery center is located; and at Boeing facilities in San Antonio (TX).

Boeing also stored planes at Moses Lake in central Washington, where Boeing often conducted flight tests; and in Victorville (CA), a popular graveyard for retired aircraft and for temporary storage of surplus aircraft during recessions or the COVID pandemic.

MAX grounding was initially considered short-lived, measured in months. The grounding ultimately lasted 21 months before regulators recertified the plane. The COVID pandemic, which began in March 2020, has exacerbated the impact on targeted operators.

During the grounding, airlines and lessors canceled around 100 orders for planes already built. Boeing resold them, but over time additional white tails were created as customers canceled additional orders or some airlines went out of business. Some lessors canceled orders when their future tenants evaporated.
Boeing retains ownership of the aircraft until delivery. It is free to swap motors as needed until then. Boeing also took seats from some planes to install them on new production planes, LNA told multiple sources. Supply chain shortages are prompting this action.


Boeing Commercial Airplanes declined to comment on its contingency plans. Instead, BCA referred only to a general statement made by Calhoun, CEO of The Boeing Co., during the 2Q2022 earnings call.

“As far as the supply chain is concerned, we continue to encounter real constraints. We are taking steps to mitigate risk in a number of areas, including engines, raw materials and semiconductors. To stabilize production and support our supply chain, we are strengthening our on-site presence at suppliers, building expert teams to address industry-wide shortages, utilizing in-house manufacturing for peak and manage inventory safety stock levels and increase if necessary,” Calhoun said.

A longer version of this information can be found at

Scott the Hamilton
Leeham News
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