Both of the 2012 ditchings almost certainly (some might say certainly) wouldn't have happened if the vibration data had been downloaded after each flight.
If you read the data from AAIB then that isn't the case
Page 9 of this relates:-
Air Accidents Investigation: S3/2012 EC225 LP Super Puma, G-REDW
But it says :-
Health and usage monitoring system (HUMS)
A review of the HUMS data showed no indication of any
significant rising vibration trends until approximately six flying hours prior to the start of the accident flight. Prior to this period, the vibration levels on indicators associated with the bevel gear vertical shaft were below the mean level established from data collected from 23 other EC225 LP helicopters.
During the last six flying hours, which covered the two flights prior to the accident flight, the trend for indicator
MOD 45, which monitors the meshing frequency of the bevel gear, and MOD 70 which monitors the meshing frequency of the oil pump wheels, increased. An amber4 alert was generated for MOD 45 following the last flight on 9 May 2012, and for both indicators following the first flight on 10 May 2012. The operator’s engineers followed the fault diagnosis chart in the Aircraft Maintenance Manual (AMM), Chapter 45.11.08.211. The washer on the accelerometer for these parameters was replaced following the first amber alert on 9 May 2012, and the MGB magnetic chip detectors were checked, and found to be free of debris, following the alerts on the 10 May 2012. Thirty six other indicators were checked
and no significant trends were detected. In accordance with the guidance in the AMM, the aircraft was placed on 10 hourly close monitoring and released for flight.
Following the accident, the helicopter manufacturer analyzed the data for indicators MOD 45 and MOD 70 and reduced the vibration level required to generate an amber alert. Red alert thresholds have also been introduced for both these indicators
5.
Footnote
4
An amber alert requires the operator to determine if a maintenance action is required, whereas a red alert requires a maintenance action
Footnote
5
Eurocopter Service Bulletin No 45-001.