Every year I get asked a version of this question: can an owner use an FAA annual inspection on a turbine-powered rotorcraft? The short answer: You bet!
While an annual inspection may not be advantageous in every case, it is a legal and viable method to maintain the airworthiness of most turbine helicopters. Airbus AS350s, Bell 429s, and even Sikorsky S-76s are eligible, provided they’re operated as a private aircraft under FAA Part 91.
What follows is my version of the long answer via a brief overview of the annual inspection process:
BACKGROUND, MYTHS, CLARIFICATIONS
First off, the owner/operator—not the mechanic—is legally responsible for an aircraft’s airworthiness and selecting its inspection program. Reference 91.403 and 91.405.
However, it is always prudent to consult with a mechanic prior to deciding on an inspection program. Each available program has its own list of pros and cons. It’s important for an owner to understand these differences before making that decision.
Now some individuals have argued an annual can’t be used on a turbine helicopter per 91.409(c)(4). Not true. Paragraph (c)(4) removes the regulatory requirement of 91.409(a)(1) when an owner elects to use an inspection program listed in 91.409(e). Actually, the owner of a private turbine helicopter has six options to choose from when selecting an inspection program.
Another misunderstanding is the belief that you only need follow the requirements in Part 43 Appendix D to comply with an annual inspection. Again, not true. The same applies to piston-powered rotorcraft. There are additional performance rules hidden in 43.15(b) and (c) that are applicable to rotorcraft and annual inspections.
Technically, an annual inspection only covers the disassembly (as needed for inspection), cleaning, inspection, and reassembly of the aircraft. Nothing more. While compliance with additional maintenance tasks may be convenient during an annual, it’s important for an owner to address these tasks as separate items, especially when looked at from a billing standpoint.
One final clarification: even though an annual inspection is selected per the exception found at the end of 91.409(e), an owner of a turbine helicopter must follow the requirements listed at the beginning of 91.409(e) relating to replacement of life-limited parts and the inspection of installed appliances, survival equipment, and emergency equipment.
The hardest part of using an annual on a turbine helicopter is finding a maintenance provider or a local mechanic with an inspection authorization (IA) who wants to do the inspection. Geographically, some areas have better resources than others.
If an owner needs to fly across state or farther for the inspection, those costs should be figured in when comparing an annual to other inspection programs. Keep in mind, an annual inspection is due only once every twelve calendar months.
Once an IA is located, the first order of business should be a proactive discussion prior to starting the annual and continuing throughout the duration of the inspection. This dialogue will keep both sides engaged and reduce the possibility of surprises during the inspection.
Topics to discuss include: the inspection checklist the IA will follow, required manufacturer (OEM) documentation, required aircraft records, how discrepancies will be addressed, and any additional maintenance to be performed.
Nothing hurts more than going in with a $1,500 annual and coming out with a $5,000 bill … or worse.
At the core of an annual inspection is the checklist the IA will use to perform the inspection. Part 43.15(c) provides guidance: “The checklist may be of the person's own design, one provided by the manufacturer of the equipment being inspected or one obtained from another source.”
The sole caveat is that the checklist must cover the “scope and detail” of Part 43 Appendix D and 43.15(b). More on Paragraph (b) in a minute.
Some individuals keep things simple by using the appendix as their checklist, exactly as it’s written in the FARs. Although it is perfectly legal to use Appendix D itself as the checklist, it should be noted this document doesn’t always offer the best inspection structure to maintain the long-term investment value of a turbine helicopter.
One alternative method is to use the OEM inspection forms as the checklist. These forms offer a comprehensive guide to the specific aircraft and engine. Plus, they provide a means of compliance with the additional requirements of 43.15(b) which includes inspecting the aircraft center section, main rotor assembly, main rotor transmission, drive shafts, and tail rotor.
Most OEM forms are included in Chapter 5 of their respective maintenance manual (MM). However, depending on the format, they could be in a different manual or chapter. For instance, Airbus lists their inspections in their Master Service Manual (MSM).
If lucky, the OEM will have an inspection form labeled “Annual,” or “Annual/100 Hour Inspection.” If not, it will take a little more digging.
Look for a basic inspection schedule spanning 12 calendar months or from 100 to 300 flight hours. There might even be a note stating which forms to use every 12 months. For example, Chapter 5 in the Bell 206L-3 MM references the 100-hour and 300-hour forms every 12 months. A similar note in the Rolls Royce C-30P MM indicates the 150-hour and 300-hour forms for the same time period. Can you dig it?
The AS350B2 with a Turbomeca Arriel 1D1 is more streamlined. Listed in the B2 MSM is a Type F inspection which is tailored to an annual inspection. The 1D1 MM (chapters 5-20) lists a single 300-hour/12- month inspection that can provide a useful checklist for an annual.
An important note on the inspection criteria: an annual inspection is a general condition check and function check of the entire helicopter. The limited criteria listed in Appendix D reflects this.
However, in some cases the OEM forms may indicate more detailed inspections (like checking engine vibration levels) that technically go beyond the scope of an annual inspection. Conversely, the OEM forms will indicate certain items not specifically mentioned in Appendix D that would be important on a turbine helicopter, such as checking magnetic chip plugs.
While OEM forms offer a number of advantages, how detailed the OEM inspection criteria will be followed should be discussed and decided on with the IA prior to starting the annual.
OEM DOCUMENTATION AND AIRCRAFT RECORDS
Even if Appendix D is used as the annual checklist, OEM documentation is still required to comply with requirements of 43.15(b) and 91.409(e). This documentation includes FAA-approved airworthiness limitations listings, OEM inspection instructions for the specialized areas listed in Paragraph (b), and applicable instructions for continued airworthiness (ICA) for optional equipment installed on an aircraft.
As for aircraft records, this is also the perfect time for an owner to ensure compliance with 91.417(a)(2). Not only are these maintenance records required by regulation, several of them will be needed to comply with the annual inspection.
Paragraph (a)(2) records include: aircraft total time-in-service, current status of installed life-limited parts, and current status of applicable airworthiness directives (ADs), to name a few.
So, the IA has finished the annual and is ready to close up, but he brings the owner a list of discrepancies. Now what?
This options exists: If prior arrangements were made to repair the discrepancies at this time, the owner is good to go. As a mechanic, the IA can fix the problems and document the work accordingly. Then as the IA, he will reassemble the aircraft, comply with required function checks, and sign off the annual approving the aircraft for return to service per 43.11(a)(4).
Although legal, there’s a second option that is not as straightforward. The IA can still complete the annual inspection, but he will sign it off per 43.11(a)(5); that is, he will disapprove the aircraft for return to service and provide the owner with a list of discrepancies per 43.11(b).
For example, the IA finds a secondary instrument inoperative during the inspection and cannot procure a replacement for an extended time. This time three options exist.
If the helicopter has an approved minimum equipment list (MEL) that provides relief for the instrument, the repair can be deferred per the allotted timeframe. If there is no MEL, a review of 91.213(d) for possible deferment can be undertaken. Or as a final option, the local FSDO can be contacted for a special flight permit.
Whichever option is selected will allow the owner to fly home and have the issue corrected by a local mechanic. Granted, a more complex discrepancy may require a different approach.
As mentioned in the beginning, other inspections and maintenance may be convenient to address during an annual inspection.
Altimeter system inspections, transponder inspections, and ELT checks have their own requirements under 91.411, 91.413, and 91.207, respectively. The same is for OEM-recommended maintenance tasks.
Component oil and filter changes, lubrication requirements, and corrosion control applications could be scheduled at this time. Annual time is also the perfect excuse to take care of those cosmetic touch-ups, upgrades, and modifications.
I hope this article answers the basic question of annuals and turbine helicopters. If you find yourself wondering about what inspection program to use on your next turbine-powered rotorcraft, contact your local IA and learn firsthand if an annual inspection will work for you.
About the author: After 32 years maintaining helicopters in various capacities, Skola concluded a full-time career with a major operator in 2014. When not pursuing writing projects, he can still be seen around the flight line providing maintenance oversight, litigation support, and technical research services. He can be contacted at firstname.lastname@example.org.