Improvement Program Slashes B-2 Maintenance, Improves Readiness
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The $2.2 billion dollar B-2 Spirit stealth bomber has long suffered from a significant problem: maintaining its stealth requires a great deal of ground work involving tape and caulking. Given the stealth is the bomber’s only real defense, flying them in compromised status is not an option. The result was predictable: very low “readiness rates” in the 30-45% range, which meant that the 21 bombers in the USA’s fleet really meant about 7-9 in the air after the initial opening phase of any conflict.
The USAF’s Materials and Manufacturing Directorate worked with the B-2 Systems Group and material processing experts; and after some initial glitches, they think they may have this problem solved. If so, readiness rates could rise to figures approaching 70-80%. That makes a big difference to a high-value asset.
So, how did all this come about?
“Inability to meet stealth requirements is the single greatest driver for the low B-2 readiness rates….Were low-observability requirements not a factor, the plane would remain relatively ready, boasting a rate closer to 80 percent mission-capable…. The Air Force is undertaking a B-2 “mission-capable rate improvement plan,” crafted by Northrop Grumman. This will replace the traditional tape and caulking material repair method with a new approach using spray-on, radar-absorbing coating.”
One of the things stealth requires is a lot of smoothness, as protrusions and indentations have a tendency to reflect radar waves. The effort at Wright-Patterson AFB in Ohio is called Alternate High Frequency Material, or AHFM.
This USAF story notes that the initial program tested well, but couldn’t scale up to production because they couldn’t get consistent batch-to-batch performance. That isn’t confidence inspiring if your life is depending on the results, so the program was postponed and cancellation was a possibility.
The program was too important to simply cancel, however, and the potential benefits were too big. Experts from the USAF’s Manufacturing Technology Division initiated a $2.8 million AHFM Rapid Response Process Improvement (RRPI) program within a week of the postponement, identifying the AHFM manufacturing problems and implementing solutions. The program was re-implemented within six months of the RRPI initiation.
The AHFM program has led to numerous improvements. For starters, the B-2 Systems Group was able to proceed with fleet-wide implementation. To date, four AHFM B-2 bombers have been delivered, and the rest of the B-2 fleet will be modified as they undergo depot maintenance.
On the manufacturing end, the material production schedule shrank from 26 weeks to 12 weeks, including an improved test method that saves eight days per batch. This seems incidental, but it was having cascading effects. Production of AHFM-like materials had previously been done in modest quantities by small specialty material manufacturers. The material can now be made in large 500-gallon batches that consistently meet tight performance specifications, which means that the manufacturer to reliably deliver material on-time and on-budget. Having the $2.2 billion bomber waiting for rolls of fabric tape or spray-on is silly, and now it isn’t necessary.
Maintenance that previously required a week of aircraft downtime for repair now require as little as 30 minutes, and the program also drops B-2 maintenance man-hours per flight-hour by 50%.
The USAF says that the results of this program have caught the attention of other weapon system program offices. While the circumstances of this particular program are rather specific, AHFM program manager Doug Carter is quoted as saying that “Lessons learned from this program are being applied to the production of new weapon systems, thereby saving the Air Force additional dollars.”
