Type: F27-500
Symptom: Knocking noise heard in climb after cleaning up and thumping felt through control column. Frequency increased during cruise and reached maximum intensity during the descent. The instant the flap was lowered, the knocking stopped. Over a month or so, the knocking got worse and worse. Cabin crew continually complaining about the bumping.
Problem 1: There was a huge hole on the leading edge of the right hand horizontal stabliser (under the de-icing boot), big enough to stick your head and shoulders through.
Problem 2: Three of the bolts used to hold the tailplane had "gone".
Solution: Replace entire tailplane.