A version of this article appears in the August 11/18 double issue of Aviation Week & Space Technology.

The F-35 Joint Strike Fighter (JSF) program will certainly recover from the embarrassment of missing its intended international debut in the U.K. last month after an engine fire grounded the fleet for 13 days. But numerous questions remain to be answered before we can be equally confident that the most costly weapons procurement in history is back on course. The engine-related grounding—the program’s fourth since January 2013—must not be approached merely on narrow technical grounds if, as we fear, there prove to be lessons to be learned about program management, as well.

The stealthy, single-engine fighter has returned only to limited flying, and the JSF program office and engine contractor Pratt & Whitney have yet to provide a detailed explanation of the June 23 fan-stage breakup that caused the grounding and what steps are being taken to assure it does not happen again.

Pratt canceled a recent public briefing on the engine failure, and there has been scant information since the middle of July on the source of the problem. The silence is disappointing but perhaps understandable, given that the accident investigation is still ongoing. But at some point, taxpayers are owed a full and open accounting of what went wrong and what steps are being taken to make sure such failures cannot happen again.

What is more, there are larger issues than technical details of the mishap itself. The most disturbing aspect of the grounding is that the F135 engine had completed engineering and manufacturing development (EMD) apparently without key issues being discovered. Unless it is truly a one-off, this sort of engine failure is normally the kind of fundamental design issue that engineers are expected to catch early in development and deal with long before flight tests even begin. That certainly raises questions about what else may have been missed during the EMD phase.

Not surprisingly, the failure of the Pratt engine has generated “I told you so” talk of whether an international development effort of this scope should have had an alternate engine as a backup. GE and Rolls-Royce were developing an advanced turbofan, dubbed the F136, as an alternative for powering JSF. The Pentagon was not enthusiastic, because of the added expense of a second engine program; some of the additional cost could be recaptured via competition between suppliers, but only some. But for several years, Congress funded the alternate engine after the Pentagon left the project out of its budget requests. Finally, in 2011, the Obama administration and partisans of Pratt succeeded in killing the F136, after an especially nasty political battle. Pratt dismissed as a scare tactic the argument that a second engine was needed to mitigate the threat of a fleet-wide grounding, and the F136 was derided as a pork-barrel initiative.

After the latest grounding, the Senate Appropriations Committee recommended to the Pentagon that it reconsider an alternate engine program. It is probably too late to unscramble the omelet. And Pentagon acquisition chief Frank Kendall argues that the further downstream the program gets, the weaker the case for an alternate engine becomes. There is no free lunch; two engines cost more, a single source presents higher risk. However, program officials should at least consider whether there is a case for a mid-life alternative engine if it can draw on advances in commercial technology to keep the cost down.

For its part, Pratt should stop concealing the cost of the taxpayer-funded engine. What rings hollow is the company’s claim that the price of an engine on which it holds a monopoly is a competitive secret.

The JSF, for which Lockheed Martin is the airframe prime contractor, has not been riding waves of good news in recent years. Initial operating capability dates have finally been set for the three variants—beginning with the short-takeoff-and-vertical-landing F-35B by next December, followed by the F-35A for land-based air forces a year later and the F-35C for aircraft carriers in February 2019. But since the program began in 2001, the average unit cost has doubled and the date to begin full-rate production has slipped seven years to 2019. Most recently, in addition to the engine fire, problems include late software deliveries and serious questions about how much it will cost to maintain the fighter.

The F-35 program director, Air Force Lt. Gen. Christopher Bodgan, has been blunt in his displeasure about the performance of JSF contractors. The question now is whether the JSF can be kept from further schedule slips and cost overruns. The issues that caused this failure need to be identified and addressed. If they are, those lessons ultimately can drive better stewardship of other defense and space procurements.