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Meggitt Combustion Heaters--Initial Regulatory Flexibility Analysis

Daniel Leach

22Feb2016

Introduction and Purpose of This Analysis

The Regulatory Flexibility Act of 1980 (Public Law 96-354) (RFA) establishes “as a 

principle of regulatory issuance that agencies shall endeavor, consistent with the objectives of the 

rule and of applicable statutes, to fit regulatory and informational requirements to the scale of the 

businesses, organizations, and governmental jurisdictions subject to regulation.” To achieve this 

principle, the RFA requires agencies to solicit and consider flexible regulatory proposals and to 

explain the rationale for their actions to assure that such proposals are seriously considered.” The 

RFA covers a wide-range of small entities, including small businesses, not-for-profit 

organizations, and small governmental jurisdictions.

Agencies must perform a review to determine whether a rule will have a significant 

economic impact on a substantial number of small entities. If the agency determines that it will, 

the agency must prepare an initial regulatory flexibility analysis (IRFA) as described in the RFA.

The FAA finds that the proposed AD would have a significant economic impact on a substantial 

number of small entities. Accordingly, in the following sections we discuss the compliance 

requirements of the proposed AD, the cost of compliance, and the economic impact on small 

entities.

Section 603(a) of the RFA requires that each initial regulatory flexibility analysis contain:

(1) a description of the reasons action by the agency is being considered;

(2) a succinct statement of the objectives of, and legal basis for, the proposed rule;

(3) a description of and, where feasible, an estimate of the number of small entities to which the 

proposed rule will apply;

(4) a description of the projected reporting, recordkeeping and other compliance requirements 

of the proposed rule, including an estimate of the classes of small entities which will be 

subject to the requirement and the type of professional skills necessary for preparation of 

the report or record; and

(5) to the extent practicable, an identification of all relevant Federal rules which may duplicate, 

overlap or conflict with the proposed rule.
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(6) Each IRFA shall also contain a description of any significant alternatives to the proposed 

rule which accomplish the stated objectives of applicable statues and which minimize any 

significant economic impact of the proposed rule on small entities.

1. Objectives of, and Legal Basis for, the Proposed Rule

Title 49 of the U.S. Code specifies the FAA’s authority to issue rules on aviation safety. 

Subtitle I, section 106, describes the authority of the FAA Administrator. Subtitle VII, Aviation 

Programs, describes in more detail the scope of the FAA’s authority.

We are issuing this rulemaking under the authority described in subtitle VII, part A, subpart 

III, section 44701, “General requirements.” Under that section, Congress charges the FAA with 

promoting safe flight of civil aircraft in air commerce by prescribing regulations for practices, 

methods, and procedures the Administrator finds necessary for safety in air commerce. This 

regulation is within the scope of that authority because it addresses an unsafe condition that is 

likely to exist or develop on the airplanes identified in this proposed Airworthiness Directive 

(AD) (79 FR 49249, August 20, 2014).

2. A Description of the Reasons Action by the Agency Is Being Considered

This proposed AD stems from the crash of a Cessna 401 near Chanute, Kansas, on May 11, 

2012, killing the pilot and three of the four passengers aboard, and seriously injuring the fourth 

passenger. According to the NTSB report, the crash occurred after dark smoke emanated from 

the cabin heater and entered the cabin obscuring the occupants’ vision. According to the Report: 

“The smoke likely interfered with the pilot’s ability to identify a safe landing site.” When the 

pilot attempted an emergency landing in a field, the airplane’s wing contacted the ground and the 

airplane cartwheeled.

The NTSB determined the probable cause of the accident to be the

malfunction of the cabin heater, which resulted in an inflight fire and smoke in the 

airplane. Contributing to the accident was the pilot’s lack of understanding 

concerning the status of the airplane’s heater system following an earlier overheat 

event and the risk of its continued use. Also contributing were the inadequate 

inspection criteria for the cabin heater.1

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 1 www.ntsb.gov, “Aviation Accident Database”, “Monthly Lists”, “2012 May”, “Friday, May 11, 2012”, “Probable 

cause (09/05/2013)”. The NTSB Accident Identifier is CEN12FA290.
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As result of this accident, the FAA is proposing this AD to detect and correct a hazardous 

condition caused by deterioration of the combustion heater, a condition that could lead to 

ignition of heater components and result in smoke and fumes in the airplane cabin.

3. A Description of and an Estimate of the Number of Small Entities to which the 

Proposed Rule Will Apply

The proposed AD would supersede AD 81-09-09, which applies to 8000 series Meggitt 

combustion heaters installed on certain twin-engine piston airplanes, primarily Cessna 300 and 

400 series airplanes, but also installed on the Beech D18S twin-engine airplane and some Britten 

Norman twin-engine piston airplanes. The proposed AD would extend applicability to 900 series 

Meggitt combustion heaters installed on certain Cessna single-engine piston airplanes, Cessna 

310 twin-engine airplanes, Lake LA-4 and LA-250 airplanes, certain Ryan Navion single-engine 

piston airplanes and certain Piper PA-23 and PA-30 airplanes. The FAA airplane registry 

indicates that there are 4121 airplanes of the models equipped with 8000 series Meggitt 

combustion heaters2

, and 2123 airplanes of the models equipped with 900 series Meggitt 

combustion heaters.3 Since many of these airplanes are registered to Limited Liability 

Companies (LLCs), Limited Liability Partnerships (LLPs) and other company forms typically 

suited for single proprietors, small partnerships, etc., we conclude that the proposed rule would 

affect a substantial number of small entities.

4. Duplicative, Overlapping or Conflicting Federal Rules

The FAA is unaware of any Federal rules that duplicate, overlap, or conflict with this

proposed rule.

5. Significant Alternatives to the Proposed Rule

Because of an unsafe condition that is likely to exist or develop on the airplanes identified in 

this proposed AD, there is no feasible significant alternative to requiring the actions of this 

proposed AD. The FAA invites public comment on this determination.

The FAA considered allowing more flight hours or calendar time before requiring 

compliance, but this alternative would increase the risk of another fatal accident. The proposed 

 2 Files downloaded to FAA Registry 30-1-2015.

3 Files downloaded to FAA Registry 23-10-2015.
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rule allows the combustion heater to be disconnected or removed, but, operating without a heater 

is unlikely to be viable.

6. Reporting, Record Keeping, and Other Compliance Requirements of the Proposed Rule

Small entities would incur no new reporting and record-keeping requirements as a result of 

this rule.

Compliance requirements

The proposed rule would carry over the following requirements from the existing AD 81-09-09:

• Conduction of the 250-hour heater inspection every 250 hours of heater operation,

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accordance with the manufacturer’s service manual. We estimate the labor cost of this 

action to be 2 hours x $85 = $170.

• General inspection of the heater installation at the same time as the 250-hour inspection.

We estimate the labor cost of this action to also be 2 hours x $85 = $170.

Since the proposed rule would extend applicability to 900 series heaters Meggitt combustion 

heaters, which are installed on certain airplanes, there is an incremental cost associated with the 

existing requirement for these two inspections. There is no incremental cost associated with 

applicability to 8000 series heaters, installed on certain airplanes, as the current rule already 

applies to these heaters.

The proposed AD would add the following new provisions, which will apply to both 900 and 

8000 series heaters installed on certain airplanes:

• During each 250-hour inspection more detailed actions would be required, namely

inspection of the thermostat and upper limit switches, and inspection of the solenoid 

valve and fuel pump.

o In conjunction with the 250-hour and installation inspections already required, the 

labor cost of these more detailed actions would be one hour of labor at $85. “Oncondition” costs to replace the temperature switches would be an additional hour of 

labor ($85) and $320 in materials cost, for a total of $405. On-condition costs to 

repair/overhaul the pump would be an additional two hours of labor ($170) and $470 

 4 More precisely, all requirement intervals are “250 hours of combustion heater operation or two years, whichever 

occurs first.”
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in materials cost for a total of 

$640.

• Operators would be required to replace defective combustion tubes with new tubes as 

repair of combustion tubes would be prohibited. We estimate the cost of prohibiting 

repair of combustion tubes to be minimal as industry reports that the Meggitt heater 

combustion tubes are effectively non-repairable.

• At the same time as the 250-hour and installation inspection, a combustion heater 

pressure decay test (PDT) would be required.

o The PDT would cost $170. If the combustion heater fails the PDT, the operator would 

be required to replace the combustion tube at an installed cost of $4,580.

• Operators have the options of disabling the heater at an estimated cost of $170 or 

removing it at estimated cost of $255.

Cost of Compliance

In calculating the cost of compliance we assume that operating without a heater is unlikely to 

be viable, as noted above. We estimate the ten-year cost of the proposed rule. Based on data in 

the 2014 GA Survey, we can somewhat conservatively assume that average flight hours per 

airplane per year are about 100 hours.5 We estimate heater time to be 50% of airplane flight

hours so, on average, flight hours will accumulate to about 1000 hours in ten years and heater 

time will accumulate to about 500 hours. Since requirements for inspection internals are “250 

hours of combustion heater operations or two years, whichever occurs first”, we expect 

inspections to usually occur every two years.” As will be seen below, compliance costs are 

dominated by the almost immediate requirement for the PDT test.6

 5 The 2014 General Aviation Survey shows the average flight hours to be 87.2 hours per year for active singleengine piston airplanes with 4+ seats, 104.8 hours per year for active twin-engine piston airplanes with 1-6 seats, 

and 157.6 hours per airplane for active twin-engine airplanes with 7+ seats. Using the flight hour figures for the first 

two categories, the weighted average for airplanes equipped with 900 series heaters is 93.6 hours and for airplanes 

equipped with 8000 series it is 128.2 hours.

6 All three actions are required to be taken “within the next 10 hours of combustion heater TIS or at the next 

scheduled 100 hr. inspection, Annual Inspection, or Phase Inspection that occurs after the effective date of this AD, 

whichever occurs first ....”
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Pressure Decay Test

The FAA estimates that 90% of combustion tubes tested will fail the first PDT test. Since 

replacing the combustion tube, like an overhaul, requires complete disassembly of the 

combustion heater, we somewhat conservatively assume that operators will overhaul their 

combustion heaters at $4,580, rather than simply replace the combustion tube, at $4900. Major 

components such as the combustion tube, fuel pump, and temperature switches that are typically 

replaced or overhauled in a combustion heater overhaul have service lives of 750 heater hours, 

equivalent to about 1,500 flight hours or 15 years. Therefore, we assume that once replaced or 

overhauled, these components will not need to be replaced during our 10-year period of cost 

estimation. So aside from the initial tube replacement, we estimate that, for inspections required 

by the proposed rule, “on-condition” costs would be minimal.

Table 1 below shows our calculation of compliance cost for airplanes with the affected 

Meggitt combustion heaters. We assume the rule to be effective in 2017 and, as discussed above, 

in the first year we assume the combustion heater fails the PDT resulting in a subsequent 

overhaul. For the 8000 series heaters note that the $935 labor cost for 2017 includes three hours 

of labor ($255) for the detailed inspection and the PDT in addition to eight hours of labor for the 

overhaul ($680).7

As the table shows, we estimate the present value cost of compliance to be $6,020 for 

airplanes equipped with 8000 series Meggitt combustion heaters and $7,514 for airplanes 

equipped with 900 series Meggitt combustion heaters. The lower cost for airplanes with 8000 

series combustion heaters reflects the previously noted fact that 8000 series heaters are currently

subject to the 250-hour inspection and installation inspection requirements, and, therefore, the 

incremental cost would be correspondingly less for airplanes with 8000 series combustion 

heaters compared to airplanes with 900 series heaters.

Economic Impact on Small Entities

If the cost of compliance is greater than 2% of the value of an operator’s airplane, the FAA 

considers the cost impact to be significant. So if the value of an airplane equipped with an 

affected Meggitt combustion heater is less than 50 times the cost of compliance, we consider that 

the operator of the airplane would incur a substantial economic impact. With a present value cost 

 7 A similar note should be made for the 900 series combustion heaters, in that case, however, taking into account an 

additional four hours of inspection time.
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of about $6,000 for airplanes equipped with 8000 series Meggitt combustion heaters, the FAA 

considers the cost impact to be significant for all such airplanes with values below about 

$300,000. With a present value cost of about $7,500 f1or airplanes equipped with 900 series 

Meggitt combustion heaters, the FAA considers the cost impact to be significant for all such 

airplanes with values below about $350,000. The airplanes equipped with the affected heaters are 

single- and twin-engine piston airplanes that, for the most part, were manufactured from the 

1940s to the 1980s, and range in price from about $350,000 for a Cessna 221C Golden Eagle 

down to a price as low as $30,000 for a Piper 23-150 Apache.8 Accordingly, most of the 6244 

airplanes equipped with Meggitt combustion heaters have values low enough to consider that the 

airplane operators would incur a significant economic impact. As noted above, many of these 

airplanes are registered to LLCs and other small companies.

The FAA therefore concludes that this proposed rule would have a significant economic 

impact on a substantial number of small entities.

 8 Aircraft Bluebook, February 2012.
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Table 1. Costs of Compliance

Airplanes with 8000 Series Meggitt Combustion Heaters

Year

Materials

Cost

Labor 

Cost

Mtls + 

Labor 

Cost Actions

Discount 

factor 

(@7%)

PV 

Cost 

2017 $ 4,220 $ 935 $5,155 

Detailed inspection (1 hr labor), PDT (2 hrs labor)--Overhaul 

after assumed failure (8 hrs labor, $4,220 materials) 1.000 $5,155 

2019 $ 255 $ 255 Detailed inspection (1 hr labor), PDT inspection (2 hrs labor) 0.873 $ 223 

2021 $ 255 $ 255 Detailed inspection (1 hr labor), PDT inspection (2 hrs labor) 0.763 $ 195 

2023 $ 255 $ 255 Detailed inspection (1 hr labor), PDT inspection (2 hrs labor) 0.666 $ 170 

2025 $ 255 $ 255 Detailed inspection (1 hr labor), PDT inspection (2 hrs labor) 0.582 $ 148 

2027 $ 255 $ 255 Detailed inspection (1 hr labor), PDT inspection (2 hrs labor) 0.508 $ 130 

 Total PV Cost: $6,020

Airplanes with 900 Series Combustion Meggitt Heaters

Year

Materials

Cost

Labor 

Cost

Mtls + 

Labor 

Cost Actions

Discount 

factor 

(@7%)

PV 

Cost 

2017 $ 4,220 $1,275 $5,495 

250-hr inspection (2 hrs labor), installation inspection (2 hrs 

labor), detailed inspection (1 hr labor), PDT (2 hrs labor)--

Overhaul after assumed failure (8 hrs labor, $4,220 materials) 1.000 $5,495 

2019 $ 595 $ 595 

250-hr inspection (2 hrs labor), installation inspection (2 hrs 

labor), detailed inspection (1 hr labor), PDT (2 hrs labor) 0.873 $ 520 

2021 $ 595 $ 595 

250-hr inspection (2 hrs labor), installation inspection (2 hrs 

labor), detailed inspection (1 hr labor), PDT (2 hrs labor) 0.763 $ 454 

2023 $ 595 $ 595 

250-hr inspection (2 hrs labor), installation inspection (2 hrs 

labor), detailed inspection (1 hr labor), PDT (2 hrs labor) 0.666 $ 396 

2025 $ 595 $ 595 

250-hr inspection (2 hrs labor), installation inspection (2 hrs 

labor), detailed inspection (1 hr labor), PDT (2 hrs labor) 0.582 $ 346 

2027 $ 595 $ 595 

250-hr inspection (2 hrs labor), installation inspection (2 hrs 

labor), detailed inspection (1 hr labor), PDT (2 hrs labor) 0.508 $ 302 

Total PV Cost: $7,514

Note: Entries may not add to totals because of rounding