Workers at a Sorrento Valley auto-repair shop arrived at work Thursday morning to find that a five-gallon bucket of cleaning solution had fallen off a military aircraft flying out of nearby Marine Corps Air Station Miramar and crashed through the roof of the business, damaging a half-dozen cars. The non-injury mishap was reported about 11 a.m., roughly 16 hours after it occurred, according to USMC officials and the San Diego Fire-Rescue Department.