At the NBAA Convention later this month in Orlando, Fla., “Manufacturers will likely emphasize the potential for rising deliveries beyond 2012, pockets of demand strength and the products they are developing,” JPMorgan aerospace analysts wrote in the firm’s latest business jet monthly report, released yesterday. “However, with U.S. and European flight ops flat to down year-to-date, Chinese demand facing pressure and OEM backlogs yet to turn up decisively, optimism should be muted.”

In the update, JPMorgan expresses concern about softening demand for large-cabin jets, which “has been a relative bright spot amid ongoing weakness across the industry.” According to its data, pre-owned inventories of large-cabin jets decreased by 0.7 percentage points in the third quarter, versus flat inventories for midsize jets and a 0.5-percentage-point decline for light jets. Meanwhile, backlogs for new-production large-cabin jets have not grown this year for Gulfstream, Bombardier (excluding NetJets orders) or Dassault, JPMorgan said. Notably, Chinese demand has fallen from elevated levels last year, and “China was a key driver of large jet outperformance out of the downturn,” JPMorgan analysts noted. “We are increasingly concerned about a correction in demand for larger jets overall.”

Overall, pre-owned inventory decreased 0.1 points to 10.5 percent last month, but young jet (up to five years old) inventory experienced its largest one-month gain since March 2009, rising to 7.5 percent.