All aircraft experience cracks, there are just so many mechanical parts that whether it is due to poor production, design that was flawed or incorrect design assumptions (ie expected aero / structural loads) there will be cracks, and length of time in service before they are discovered is no guarantee of 'goodness'. It might just mean the maintainers aren't looking hard enough or in the right areas so they don't find them for a long time or the aircraft may just not be conducive to finding them ie the design does not allow easy inspection until it enters a major servicing.
Of course cracks are not good but like everything in life there are a range of measures that need to be taken to manage / rectify the situation. It just depends what level of perceived safety you want, in Mr Purvinas (sp??) world it seems nothing less than 100% safe is acceptable which is surprising because flying, like everything, has risks that cannot be mitigated to nothing. If the risk of leaving the inspection / change-out of the part improves safety by 1x10E-11 accidents per flight hour (ie bugger all but the sort of levels that start to interest regulators) but would ground aircraft fleets for months and probably lead to airline shut-downs then that doesn't seem to a prudent path to take given the safety improvement vs just waiting to the next major servicing is negligible.
For anyone thinking the A380 is a fundamentally flawed design - well you might be right (time may tell), but not based on the info we all have to date. This current cracking seems to be another one of the thousands discovered in all airframes over the years and is being managed accordingly. Here is an extract from a 747 Airworthiness Directive from 1970 - surprisingly, it is about cracks in what then was a very new airframe type.
DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 39
Amendment 39-1078; AD 70-11-01
DATES: Effective September 15, 1970.
Regulatory Information
70-11-01 BOEING: Amdt. 39-992 as amended by Amendment 39-1078. Applies to Boeing Model 747-100 Series airplanes.
Compliance required within the next 40 flights after the effective date of this AD on aircraft having 960 or more flights, and thereafter at intervals not to exceed 40 flights from the last inspection.
To detect cracking in the wing trailing edge aft flap support arms of Boeing Model 747-100 series airplanes accomplish the following or an alternate procedure approved by the Chief, Aircraft Engineering Division, FAA Western Region.
(a) Inspect the wing trailing edge aft flap support arms for cracks in accordance with Boeing Alert Service Bulletin No. 27-2024, or later FAA approved revision.
(b) If no crack is found, repeat the inspection for cracks at intervals not to exceed 40 flights.
(c) If crack is found:
(1) and the crack length is 0.4 inches or greater, replace flap support arm with a serviceable part of the same part number in accordance with Boeing ASB 27-2024 (or later FAA approved revision) before further flight. After replacement repeat visual inspection per (b).
(2) and the crack length is less than 0.4 inches, the part may be continued in service provided that no more than one cracked support arm per flap panel exists. Parts so continued in service must be inspected at intervals not to exceed 20 flights, subject to the provisions of (c)(1) above.
(d) Repetitive inspections may be discontinued upon replacement of the existing aft flap support arm assemblies with new, improved support arm assemblies per Boeing Service Bulletin No. 27-7024, revision 2, or later FAA approved revision. Replacement of an existing support arm assembly with the new improved support arm assembly eliminates inspection requirement at that location only.
Amendment 39-992 effective May 25, 1970.
This Amendment (39-1078) becomes effective September 15, 1970.
