Missed Lightning-Strike Damage After an Anchoring Entry
During a scheduled 100-hour inspection, an AME is asked to examine the composite wingtip and metallic attach points of a light twin after a reported lightning strike. The pilot's report says 'minor scorch mark on the tip'; the previous engineer has already written 'no damage found' in the work pack. The hangar lighting is fluorescent and the inspection is being done from a stepladder with a hand torch. The AME has 30 minutes before the aircraft is due to move to the paint shop. They look at the area from the same angle as the previous engineer and see only a small paint blister. No mirror, magnifier, or tap test is used. The aircraft is later found to have underlying composite delamination and a loose bonding strap.
1. Explain the human factors that allowed the lightning-strike damage to be missed, including the role of the previous entry.
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The previous 'no damage found' entry acts as an anchor. It creates expectation bias: the second AME expects to confirm a minor paint blister rather than search for hidden damage. Confirmation bias then favours the interpretation that matches the earlier finding. The inspection is also compromised physically: fluorescent hangar light and a hand torch from a stepladder give poor angled illumination, and the same viewing angle is repeated, so a shadowed delamination or loose bond is easy to miss. Time pressure from the paint-shop slot encourages a quick look rather than a systematic search. No mirror, magnifier or tap test means the method cannot detect subsurface or hidden-area defects. Complacency is present because lightning strike is treated as a cosmetic event. The human error is therefore not simply 'carelessness'; it is a predictable interaction of anchoring, inadequate access and lighting, and schedule pressure.
2. Describe a correct inspection process for this task, including what should be recorded.
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A correct process starts with the maintenance manual, structural repair manual and lightning-strike inspection guidance, not with the previous entry. The AME should clean the area, use good direct and angled lighting, and gain proper access with a platform rather than a stepladder. Inspection should include both wingtips for comparison, a magnifier and mirror for hidden surfaces, and a tap test or other approved method for composite delamination. Metallic attach points and bonding straps should be checked for pitting, arcing, looseness and correct bonding. If guidance requires NDT, that should be done by a qualified person. The record should state the inspection method, lighting and access used, findings by location, any NDT results, and photographs where practicable. It should not say only 'no damage found'. An independent check should confirm the inspection was completed, especially where a previous entry exists.
3. What should the AME do if they are asked to release the aircraft before a proper inspection can be completed?
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They should refuse to release the aircraft and explain that the inspection method is not adequate to detect the suspected damage. The paint-shop slot is an operational convenience, not an airworthiness justification. The AME should record the inspection as incomplete, state what is needed (access, lighting, tap test, NDT or independent inspection), and escalate to the maintenance controller or quality manager. They should not rely on the earlier 'no damage found' entry as evidence. If the aircraft is moved, it should be under a clearly documented non-release status until the inspection is completed. The AME should also consider a mandatory occurrence report if a lightning strike with possible hidden damage was previously signed off without adequate inspection. The professional judgement is that uncertainty about a primary structure after a lightning strike is not something to resolve by schedule pressure.