Imagine starting a turbine engine when a battery voltage drop turns your avionics dark, even for a moment. Your Interstage Turbine Temperature (ITT) display goes black, and so does the automatic overtemp protection that's supposed to abort the start if ITT exceeds limits.

The revised Pilot's Operating Handbook (POH) language spells out exactly how narrow that safety margin is: if there's a loss of avionics or engine indications "even momentarily," the pilot's only correct response is to shut the engine off, abort the flight, and send it to maintenance to check for an ITT exceedance, because after the fact, there is no way to know whether one occurred.

For Pilatus PC-12/47E operators, that was a real risk.

‍Field Notes: The AD's compliance action is purely operational, no part number, no shop visit, just a POH insert. EASA issued AD 2025-0201 on September 18, 2025, and the FAA adopted it as AD 2026-15-07, a final rule published July 30, 2026, and effective September 3, 2026. It requires operators to insert Temporary Revision (TR) No. 31 into Section 4 (Normal Procedures) of the POH within 30 days of the effective date (October 3, 2026, for U.S. operators).

• Applicability: PC-12/47E, manufacturer serial numbers 1720 and 2001 through 2999.

What Changed, Line by Line

‍TR No. 31 makes two specific edits to Section 4-5-01 (Engine Start):

1. EPECS Note Clarification: It appends a clause stating that automatic abort-on-ITT-exceedance protection specifically does not apply during a loss of avionics/engine indications. The system can only auto-abort if it can read the ITT; when indications go dark, that safety net silently disappears.
2. New Step 11: Inserts a step ahead of the rest of the checklist mandating that any loss of indications, however brief, requires ENGINE switch OFF, aborting the flight, and reporting to maintenance.

The Debate During Rulemaking

‍When EASA posted this fix for public consultation in August 2025, it received zero comments. The debate only surfaced five months later during the FAA's comment period:

• Placement: One commenter wanted the text printed directly in 4‑5‑01. FAA responded that the AD already mandates inserting TR No. 31 into Section 4.
• Formatting: Another commenter wanted a Warning/Caution. FAA declined, noting Pilatus POH style conventions govern emphasis.
• QRH Coverage: A third commenter noted that Quick Reference Handbooks (QRH) checklists were not updated. FAA said Pilatus is updating factory QRHs, but if operators develop their own checklists, they must update them to match this POH change.

Why This Matters for Maintenance and Audits

‍An unmonitored ITT exceedance during a dark-screen start won't immediately shed a blade; it silently bakes the turbine, eroding hot-section life and setting up an engine failure hours down the line. Because the event leaves no automated digital record when avionics drop offline, pilot recognition of a momentary blackout and their follow-through on shutting down are the only barriers against cumulative thermal damage.

That's also the trap in evaluating this AD as "paperwork-only." The FAA estimates that the compliance burden is minimal. But the procedure it institutes is not cheap the moment it's triggered; any actual loss of avionics during start mandates an aborted flight and reporting to maintenance for possible ITT exceedance.

‍The AD is inexpensive. The event it guards against is not.

‍Paperwork-only ADs remain the easiest to miss during a logbook review. There's no part number to trace, no repair station signature required. This AD explicitly permits an owner/operator holding at least a Private Pilot Certificate to revise the POH and log compliance under 14 CFR 43.9(a) and 91.417(a)(2)(v).

That spares operators an unnecessary shop visit, but it also means the only footprint is a revised POH page and a one-line record entry. If that entry is missing or vague, there's no way to tell "complied with but under-documented" from "never actually revised."

Furthermore, both EASA and the FAA explicitly call this an interim action, with additional rulemaking possible pending ongoing manufacturer investigation. TR No. 31 may be the stopgap, not the ending.

‍For the auditors and IAs: When reviewing legacy records during a pre-buy, how does your shop verify compliance with POH-only ADs, and confirm that the checklist in the cockpit actually reflects the revision?

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