* Incident at GKN Aerospace factory in May compounded

shortage of passenger and cockpit windows

* GKN produces windows for planes including Boeing 737 MAX,

Airbus A220 and A350

* Boeing ( BA ) has told airlines to manage current windows

inventory

By Allison Lampert

Aug 3 (Reuters) - Planemakers, airlines and repair shops are

conserving aircraft windows after an incident at a key

California factory worsened shortages of a part needed for both

new aircraft and routine maintenance, companies and industry

sources said.

GKN Aerospace, one of the world's biggest suppliers of

cockpit and passenger windows, halted production in late May at

its factory in suburban Los Angeles after an overheating tank

raised fears of an explosion and prompted the evacuation of

50,000 nearby residents for several days.

While the incident has not derailed new plane production or

airline operations, sources and executives said, it has led to

parts delays and industry concerns over the supply of cockpit

and passenger windows.

U.S. planemaker Boeing ( BA ) said it had communicated with

operators on steps to manage window inventories after the

incident.

Boeing ( BA ) advised airlines to replace windows only when

necessary rather than for other reasons, such as aesthetics,

according to a source at a North American carrier.

Boeing ( BA ) said in a statement it continues "to work with our

supplier and are taking steps to mitigate any potential

impacts."

GKN, owned by London-listed Melrose Industries,

produces windows for several Boeing ( BA ) models including the 737

MAX, along with rival Airbus' A220 and A350 jets.

Melrose said on Friday it was working to restore the now

partially opened window factory to full production by the end of

2026.

The shortages highlight some lingering post-pandemic

weaknesses in the aerospace supply chain despite noticeable

improvements in parts availability this year.

Companies and analysts say demand from planemakers

increasing aircraft production is colliding with demand from

maintenance shops needing replacement windows to keep aircraft

flying, echoing engine shortages.

"There is a significant aftermarket for windows," said

Matteo Peraldo, aerospace and defense partner at AlixPartners.

"So the demand is not just production but is also compounded

with the aftermarket."

Airbus has experienced A220 window shortages, but that had

not delayed production, according to a source familiar with the

program.

A spokesperson for the A220 program said with GKN Aerospace

restarting production, they are "seeing positive progress so far

toward a return to normal."

Maintenance provider Lufthansa Technik said the

supply of aircraft windows for planes from both major aircraft

manufacturers had long been strained.

"Lead times have increased substantially, while procurement

costs have risen markedly," Lufthansa Technik said.

For most Boeing ( BA ) aircraft it services, window supply is often

limited to instances when the part is absolutely needed to fix a

grounded aircraft, Lufthansa Technik said.

PRIVATE JETS

Challenges in window supply have also impacted private jet

makers including Canada's Bombardier and Brazil's

Embraer ( EMBJ ), along with repair shops.

On Thursday, Bombardier CEO Eric Martel told reporters the

incident's impact on window supply is among the supply chain

challenges "we've had to manage." GKN Aerospace produces windows

for the company's flagship Global 8000 jet.

Private and commercial jet maker Embraer ( EMBJ ) had

already faced supply constraints for aircraft windows, and the

GKN incident was causing fresh concern, a source said.

Kenn Ricci, chairman of private jet operator Flexjet, which

flies Embraer Phenom and Praetor jets, told U.S. podcast

Technology Business Programming Network in February that windows

posed a problem for Embraer's ( EMBJ ) supply chain.

"If you ask Embraer ( EMBJ ), ask (Executive Jets President) Mike

Amalfitano, ask them why are your deliveries slipping, they say

it's the windows," Ricci said.

Flexjet declined to comment. Embraer ( EMBJ ) did not respond to

repeated requests for comment.