soddim,
initially we (the groundcrew) thought that the a/c had indeed had an AC failure. This was endemic with our Lightnings and caused the pilots and electricians much grief. I well remember one of our a/c came back with an AC failure and the SOP was for him to keep the engines running whilst it was investigated. On this occasion the JENGO and the EE rep climbed up on the wing with an AVO and opened the spine. The pilot followed their instructions and opened the throttles. As the 'letterboxes' opened the AVO probes disappeared down them ! This of course in front of a large audience. One a/c with AC failure and now requiring an engine change.
The job of investigating these problems was handed back to the 'leckies'.
'Interesting times' as the Chinese say