What it does
This Airworthiness Directive (AD/RB211/35 Amdt 2) requires targeted non‑destructive testing of High Pressure (HP) turbine discs in a defined sub‑population of Rolls‑Royce RB211‑524 series engines. Mechanically, the AD mandates an eddy current inspection of the HP turbine disc "in accordance with Section 3 - Accomplishment instructions of Rolls Royce NMSB 72‑AE718 original issue or later EASA approved revision" (Requirement paragraph). The AD also recognises two alternative inspection records as meeting the requirement: prior inspection under Rolls‑Royce NMSB 72‑C816, or the focussed inspection per Rolls‑Royce TS594‑J Overhaul Process Manual Task 70‑00‑00‑200‑223, provided that such prior inspection was performed when the disc had greater than 700 cycles since new (Requirement paragraph).
The directive identifies applicability narrowly by part number and serial number. Table 1 and Table 2 embedded in the AD list affected HP turbine disc part numbers (for example FK24651, FK24790, UL23166, UL29472, UL29473, UL24994, etc.) and multiple serial number ranges. The AD explicitly excludes HP turbine discs that are "pre modification Service Bulletin (SB) 72‑7730, post modification SB72‑C109 or post modification SB72‑C762" (Applicability paragraph).
Compliance is time‑and‑usage framed. For the bulk of affected discs fitted to RB211‑524 engine marks (excluding RB211‑524D4 variants), the AD sets two alternative timing rules depending on cycles since new as at 24 November 2005: discs with more than 6,150 cycles on that date must be inspected within 500 cycles from 24 November (Compliance 1(a)); discs with fewer than 6,150 cycles must be inspected by whichever occurs sooner of prior to reaching 6,650 cycles, or at the next relevant shop visit where the HP turbine rotor is removed and the disc life is greater than 700 cycles since new (Compliance 1(b)(i)-(ii)). For RB211‑524D4 variants, the numeric thresholds are 5,000/5,500 cycles respectively, with the same 700 cycles minimum life requirement for the inspection to be applicable (Compliance 2). For other listed HP turbine discs not tabulated in Table 2, inspection is required at the next shop visit where the rotor is removed and the disc life exceeds 700 cycles since new (Compliance 3).