AIR CARRIERS’ OUTSOURCING 

OF AIRCRAFT MAINTENANCE 

Federal Aviation Administration 

Report Number: AV-2008-090 

Date Issued: September 30, 2008 
 

U.S. Department of 

 Memorandum

Transportation 

Office of the Secretary 

of Transportation 

Office of Inspector General 

Subject: ACTION: Review of Air Carriers’ Outsourcing 

of Aircraft Maintenance 

Federal Aviation Administration 

Report Number AV-2008-090 

Date: September 30, 2008 

From: David A. Dobbs 

Principal Assistant Inspector General 

 for Auditing and Evaluation 

Reply to 

Attn. of: JA-1 

To: Acting FAA Administrator 

At the request of the House Committee on Transportation and Infrastructure, we 

reviewed the Federal Aviation Administration’s (FAA) oversight of air carriers’ 

outsourced aircraft maintenance. As of July 14, 2008, there were 4,159 domestic 

and 709 foreign repair stations certificated by FAA to perform maintenance on 

U.S. aircraft. When an air carrier uses an FAA-certificated repair station to repair 

its aircraft or parts, the repair station’s organization becomes an extension of the 

air carrier’s maintenance organization. 

Our audit objectives were to (1) identify the type and quantity of maintenance 

performed by external repair stations and (2) determine whether FAA is 

effectively monitoring air carriers’ oversight of external repair stations’ work and 

verifying that safety requirements are met. Exhibit A details our audit scope and 

methodology, and exhibit B lists the entities we visited or contacted. 

BACKGROUND 

Our work on outsourced maintenance has continually found that the issue is not 

where maintenance is performed but that maintenance requires effective oversight. 

Outsourced maintenance requires a multifaceted, risk-based oversight approach, 

and it is important that each of these elements work together successfully (see 

table 1 below). 

i
 

Table 1. Multiple Oversight Roles Involved in Outsourced Maintenance 

Title Oversight Role 

FAA Certificate 

Management Inspector 

(CMO) 

Assesses whether air carriers’ maintenance oversight 

programs ensure domestic and foreign repair stations use 

carrier procedures when repairing aircraft and parts. 

FAA Flight Standards 

District Office Inspector 

(FSDO) 

Ensures that FAA-certificated domestic repair stations 

meet FAA standards. 

FAA International Field 

Office Inspector (IFO) 

Ensures that FAA-certificated foreign repair stations meet 

FAA standards. 

Foreign Aviation 

Authority Inspector 

Through agreements with Germany, France, Ireland, and 

Canada, certifies and oversees FAA-certificated or U.S. 

carrier-used aircraft repair stations in these countries 

(FAA has reserved the right to do random spot 

inspections). 

Air Carrier Auditor Conducts pre-contract award and periodic follow-up 

audits of repair stations. 

Air Carrier On-Site 

Technical Representative 

Provides full-time quality control at repair stations 

performing heavy aircraft checks to ensure they comply 

with the contract, FAA standards, and air carrier 

requirements. 

Repair Station Auditor Conducts internal and external audits to ensure repair 

station and its subcontractors comply with FAA and air 

carriers’ standards. 

When we reported on air carriers’ use of FAA-certificated repair stations in 2003,1

we recommended that FAA place greater emphasis on repair station oversight 

rather than air carriers’ in-house maintenance facilities by (1) determining trends 

in air carriers’ use of repair stations; (2) identifying heavily used repair stations 

and performing frequent, detailed reviews; and (3) ensuring that foreign 

authorities follow FAA standards in conducting inspections and provide FAA with 

adequate documentation. In response, FAA began working closely with foreign 

authorities to improve the surveillance they perform on FAA’s behalf and 

implemented two new systems—one for inspectors to collect better information on 

the quantity of repairs maintenance providers perform and one to provide riskbased oversight for repair stations. 

Our 2007 testimony before the House Transportation and Infrastructure 

Committee stated that FAA needed to be vigilant in locating and monitoring the 

most critical maintenance and ensuring inspectors are well-positioned and 

properly trained to adequately oversee outsourced aircraft repairs.2

 

1

 OIG Report Number AV-2003-047, “Review of Air Carriers’ Use of Aircraft Repair Stations,” July 8, 2003. 

OIG reports are available on our website: www.oig.dot.gov. 2

 OIG Testimony Number CC-2007-035, “Aviation Safety: FAA’s Oversight of Outsourced Maintenance Facilities,” 

March 29, 2007. 

ii
 

RESULTS IN BRIEF 

Air carriers are increasingly outsourcing maintenance to repair stations to reduce 

operating costs. The nine major air carriers we reviewed3

 sent 71 percent of their 

heavy airframe maintenance checks to repair stations in 2007, up from only 

34 percent in 2003 (see figure 1). This work includes performing complete 

teardowns of aircraft that can take up to 7 weeks to complete. 

At these nine carriers, foreign 

repair stations performed 

27 percent of outsourced heavy 

airframe maintenance checks 

in 2007, up from 21 percent in 

2003. While air carriers are 

increasingly contracting with 

foreign companies for heavy 

airframe maintenance, foreign 

companies are also sending 

work to the United States. 

With the growing outsourcing 

trend, FAA and air carriers must continually improve their oversight of repair 

stations to ensure that safety measures keep pace with the changing nature of the 

industry. Although FAA has taken important steps to move its safety oversight 

toward a risk-based system, the Agency still faces challenges in determining 

where the most critical maintenance occurs and ensuring sufficient oversight. 

Figure 1. Percentage of Heavy Airframe Maintenance Checks 

Outsourced for Nine Major Air Carriers, 2003 to 2007 

1274 1126 1208 1212 1163

907

815

662

385 455

0

200

400

600

800

1000

1200

1400

2003 2004 2005 2006 2007

Calendar Year

Total Checks

Total checks Total outsourced

34% 38%

57%

67%

71%

Source: Air carrier data 

FAA needs to improve its system for determining how much and where 

outsourced maintenance is performed. FAA set up a system in fiscal year (FY) 

2007 for air carriers and repair stations to report the volume of outsourced repairs; 

however, we found this system is inadequate as these reports are not mandatory. 

Further, when carriers do voluntarily report this information, FAA does not 

require that they list all repair stations performing repairs to critical components4

or that FAA inspectors validate the information. Air carriers are only requested to 

report their top 10 substantial maintenance5

 providers. As a result, the system 

provides only limited data for FAA to use in targeting inspections. FAA plans to 

issue revised guidance by the end of calendar year 2008 that will require carriers 

3

 AirTran Airways, Alaska Airlines, America West Airlines, Continental Airlines, Delta Air Lines, JetBlue Airways, 

Northwest Airlines, Southwest Airlines, and United Airlines. American Airlines, the largest U.S. air carrier, has 

retained its heavy maintenance as opposed to making a significant shift to outsourcing; therefore, we did not include 

its outsourcing data in our review since it could skew the resulting data. 4 For the purposes of this report, we use the term “critical components” to identify those components that are 

significant to the overall airworthiness of the aircraft, such as landing gear, brakes, and hydraulics. FAA does not 

use this term or include these types of components in its definition of substantial maintenance. 5

 FAA defines substantial maintenance as major airframe maintenance checks; significant engine work (e.g., complete 

teardown/overhaul); major alterations or major repairs performed on airframes, engines, or propellers; repairs made 

to emergency equipment; and/or aircraft painting. 

iii
 

to report the volume of repairs they outsource. However, the revisions, as 

currently drafted, still do not require air carriers to report volume data for all 

repairs of critical components and inspectors to validate the data. 

Gathering adequate data to target inspections is important since FAA does not 

have a specific policy governing when CMO inspectors should initially visit repair 

stations performing substantial maintenance for air carriers. Instead, FAA allows 

inspectors to rely on the air carriers’ initial audits as a basis for approval. FAA 

permits this practice even if inspectors have found problems with the carrier’s 

audit processes. 

As a result, we found significant delays between FAA’s initial approval of repair 

stations and its first inspections at those locations. For example, over a 3-year 

period, CMO inspectors for an air carrier inspected only 4 of its 15 substantial 

maintenance providers. Among those uninspected was a major foreign engine 

repair facility. CMO inspectors did not visit this facility until 5 years after FAA 

approved this facility for carrier use—even though the repair station had worked 

on 39 of the 53 engines repaired for the air carrier. 

At other repair stations that did not receive timely CMO inspections, problems 

existed, such as untrained mechanics, lack of required tools, and unsafe storage of 

aircraft parts. While these problems were not immediate safety-of-flight issues, 

they could affect aircraft safety over time if left uncorrected. Without on-site FAA 

inspections, there is no assurance that oversight of repair stations performing 

substantial maintenance will be sufficient. FAA either needs to conduct an on-site 

inspection before approving facilities for use or verify that the air carrier’s audit 

process is effective. 

FAA needs to ensure carriers and repair stations have strong oversight 

systems. In addition to their own inspections, FAA inspectors must ensure that air 

carriers and repair stations have strong audit systems to correct identified 

deficiencies, as FAA relies heavily on air carriers’ oversight. While all the 

carriers we visited had audit programs, we found that these programs were not 

always effective. As a result, maintenance problems either went undetected or 

reoccurred. 

FAA has no requirement for when carriers must conduct a follow-up audit and 

allows carriers to close findings based on written statements from repair stations 

that they will take corrective actions. Therefore, it is critical that FAA inspectors 

closely review air carrier audit findings; validate, while on site, that repair stations 

corrected deficiencies; and fully document their results. 

For example, at one heavy airframe repair station, all three types of oversight 

failed—FAA, air carrier, and repair station. We found that two air carrier audits 

and two FAA inspections (CMO and FSDO) failed to detect significant 

iv
 

weaknesses at this facility. These were not discovered until another major air 

carrier’s pre-contract award audit found problems in the repair stations’ 

maintenance practices, such as not properly overseeing subcontractor 

maintenance. The problems identified were so serious that repair station 

management stopped operations for over a month so it could take corrective 

actions. 

In addition to periodic audits, air carriers have on-site personnel to monitor repairs 

at heavy maintenance repair stations. However, FAA does not have any guidance 

on how these personnel should examine and document their inspections, which has 

resulted in an inconsistent level of oversight. For example, on-site personnel for 

two carriers we reviewed only performed undocumented, on-the-spot inspections 

of work at repair stations. As a result, the air carriers could not use the data for 

trend analysis or ensure the repair station took corrective actions. 

FAA needs to improve processes for documenting inspection results. We also 

found that FAA inspectors did not consistently document or share inspection 

results. We reported similar problems in 2003. In response, FAA began requiring 

inspectors to include repair station names on inspection reports and document 

areas that were inspected, the results, and corrective actions taken in the national 

inspection database. However, we found the problem persists as FAA does not 

have controls to ensure that inspectors adhere to this requirement or initiate 

contact with other inspectors who may be reviewing the same repair station. As a 

result, inspectors had incomplete data to prepare risk assessments, and identified 

deficiencies went uncorrected. 

For example, in one case we found that an inspector did not enter inspection 

results in the database despite finding serious errors at a repair station that affected 

24 nose landing gears repaired over 2 years for 1 of 3 air carriers using the facility. 

This type of data is critical to FAA’s ability to perform risk-based assessments. 

To illustrate, at the time of our review, this repair station had not received on-site 

monitoring by CMO inspectors for air carriers using this facility for at least 

5 years.

FAA should expedite actions to ensure air carriers better define their 

maintenance procedures. We found that FAA does not require air carriers to 

have specific guidance for outsourced repairs. Although FAA requires repair 

stations to follow air carriers’ manuals, these manuals have been traditionally 

geared toward in-house maintenance. Since repair stations may perform repairs 

for various air carriers, all with different in-house procedures, FAA should ensure 

that air carriers provide repair stations with well-defined maintenance procedures. 

FAA recognizes the significance of this problem and is developing a rule to 

require specific language in air carriers’ manuals for maintenance completed by 

v
 

vi

external repair facilities. While this is an important step, the rule has been 

indefinitely delayed. We are recommending that FAA take interim actions such as 

encouraging written agreements between air carriers and repair stations to clearly 

define maintenance responsibilities and processes. 

SUMMARY OF RECOMMENDATIONS 

We recommend that FAA enhance its oversight of air carriers’ outsourced aircraft 

maintenance through several actions: (1) develop and implement an effective 

system to determine how much and where critical maintenance is performed and 

ensure CMO inspectors conduct initial and follow-up inspections to adequately 

assess risks at substantial maintenance providers, (2) require inspectors to perform 

detailed reviews of air carrier and repair station audits and corrective actions, 

(3) establish controls to ensure inspectors document inspection findings in the 

national database and review related findings by other inspectors, (4) ensure that 

air carriers have specific guidance for outsourced repairs, and (5) encourage air 

carriers and repair stations to develop agreements that clearly define maintenance 

processes and responsibilities. We are making a total of seven recommendations, 

which are listed on page 19. 

SUMMARY OF AGENCY COMMENTS AND OFFICE OF 

INSPECTOR GENERAL RESPONSE 

We provided FAA with our draft report on August 22, 2008, and received FAA’s 

formal response on September 26, 2008. FAA concurred with all seven 

recommendations and agreed to take corrective actions. 

For two recommendations, however, we are requesting that FAA provide 

additional information as FAA’s response and planned actions did not fully 

address our intent. FAA’s comments, our response, and actions required are fully 

discussed on pages 20 through 21. FAA’s response is included in its entirety in 

the appendix to this report. 

We appreciate the courtesies and cooperation of FAA representatives during this 

audit. If you have any questions concerning this report, please contact Lou Dixon, 

Assistant Inspector General for Aviation and Special Program Audits at 

(202) 366-0500 or Robin Koch, Program Director, at (404) 562-3770. 

# 

cc: FAA Chief of Staff 

 FAA Associate Administrator for Safety 

 Anthony Williams, ABU-100 

 Martin Gertel, M-1 
TABLE OF CONTENTS 

FINDINGS ................................................................................................... 1

Air Carriers Are Increasingly Using Contract Maintenance 

Providers To Perform Substantial Maintenance..................................... 1

FAA Needs To Improve Its System for Determining How 

Much and Where Outsourced Maintenance Is Performed 

and Ensure Sufficient Inspection Coverage ........................................... 2

FAA Relies Heavily on Air Carrier and Repair Station 

Audits, Which Are Not Always Sufficient To Correct 

Identified Deficiencies ............................................................................ 7

FAA Needs To Improve Its Inspection Data Documentation................ 14

FAA Should Ensure That Air Carriers Have Well-Defined 

Processes and Responsibilities for Outsourced 

Maintenance......................................................................................... 17

RECOMMENDATIONS............................................................................. 19

AGENCY COMMENTS AND OFFICE OF INSPECTOR 

GENERAL RESPONSE............................................................................ 20

EXHIBIT A. SCOPE, METHODOLOGY, AND PRIOR WORK................ 22

EXHIBIT B. ENTITIES VISITED OR CONTACTED ................................ 24

EXHIBIT C. MAJOR CONTRIBUTORS TO THIS REPORT ................... 27
1

FINDINGS 

Air carriers are increasingly outsourcing maintenance to repair stations to reduce 

operating costs. While FAA has taken important steps to move its safety oversight 

toward a risk-based system, we found it still relies too heavily on air carriers’ 

oversight procedures, which are not always sufficient. Specifically, we 

determined that FAA did not (1) have an adequate system for determining how 

much and where the most critical maintenance occurs; (2) have a specific policy 

governing when CMO inspectors should visit repair stations performing 

substantial maintenance; (3) require inspectors to validate that repair stations have 

corrected deficiencies identified in air carrier audits; and (4) have adequate 

controls to ensure that inspectors document inspection findings in the national 

database and review related findings by other inspectors. As a result, FAA could 

not effectively target its inspection resources to those repair stations providing the 

highest volume of repairs, which caused deficiencies at repair stations to go 

undetected or reoccur and prevented inspectors from obtaining sufficient data to 

perform comprehensive risk assessments. 

In addition, since many air carriers do not differentiate between in-house and 

outsourced maintenance, FAA must ensure air carriers provide repair stations with 

clearer guidance on how to perform maintenance and inspections at repair stations. 

FAA is working to address this issue through a rulemaking change but needs to 

pursue actions in the interim to establish agreements between air carriers and 

repair stations on how maintenance is to be performed. 

Air Carriers Are Increasingly Using Contract Maintenance Providers 

To Perform Substantial Maintenance 

Overall, major air carriers6

 outsourced an average of 64 percent of their 

maintenance expenses in 2007, compared to only 37 percent in 1996. This work 

includes everything from repairing critical components, such as landing gear and 

engine overhauls, to performing heavy airframe checks. 

The nine air carriers we reviewed sent 71 percent of their heavy airframe 

maintenance checks to contract maintenance providers in calendar year 2007, up 

from 34 percent in 2003. Foreign repair stations completed 246 (27 percent) of 

these carriers’ 907 heavy airframe maintenance checks outsourced in 2007, up 

from 21 percent in 2003. These maintenance checks were performed worldwide at 

22 repair stations located in the United States, Canada, Mexico, Central America, 

and Asia (see figure 2 on page 2). 

 

6

 Alaska Airlines, America West Airlines, American Airlines, Continental Airlines, Delta Air Lines, Northwest 

Airlines, Southwest Airlines, United Airlines, and U.S. Airways. These are the major air carriers we have been 

monitoring since our last report in 2003. These carriers all outsource various levels of maintenance, including heavy 

airframe. 

Findings 
2

Figure 2. Locations of Repair Stations That Performed Heavy 

Airframe Maintenance for Nine Major Air Carriers in 2007

United 

States

661 

81 

Central 

America 

Asia 

79 

17 

Mexico 

Canada

69 

Source: Air carrier data 

While air carriers are increasingly contracting with foreign companies for heavy 

airframe maintenance, foreign companies are also sending work to the United 

States. There are approximately 1,200 FAA-certificated repair stations in the 

United States that also have European Aviation Safety Agency certifications, 

which allow them to perform repairs for foreign companies. Nationwide data are 

not available for the amount of work that is coming into the United States; 

however, data we obtained from 1 air carrier disclosed that 11 (24 percent) of the 

46 customers using the air carrier for maintenance were foreign companies. In 

addition, some airlines, such as American Airlines, perform all heavy airframe 

maintenance in-house. 

FAA Needs To Improve Its System for Determining How Much and 

Where Outsourced Maintenance Is Performed and Ensure Sufficient 

Inspection Coverage 

With the growing outsourcing trend, FAA has taken important steps to move its 

safety oversight toward a risk-based system. Further actions are needed, however, 

as we identified problems with the frequency of inspections at 5 of the 15 repair 

stations we reviewed, all of which performed a significant volume of substantial 

maintenance for their air carrier customers. We determined that FAA needs to 

improve its inspection coverage of outsourced maintenance by requiring 

comprehensive data on how much and where critical maintenance is performed 

and ensuring CMO inspectors perform initial and recurring on-site visits to repair 

stations so that potential problems are identified and properly addressed. 

Findings 
3

FAA Still Does Not Have Comprehensive Data on How Much and Where 

Outsourced Maintenance Is Performed 

In 2003, we recommended that FAA determine what type of repairs air carriers 

send to repair stations and which repair stations carriers use the most. In response, 

FAA implemented a system in FY 2007 for both air carriers and repair stations to 

submit quarterly utilization reports. These reports are supposed to show carriers’ 

or repair stations’ maintenance providers that have the highest volume of 

maintenance activity and perform the most critical maintenance. We are 

concerned, however, about the completeness and accuracy of the data submitted 

because FAA does not require air carriers to (1) report all high-volume repair 

stations or (2) consistently categorize all repair stations that provide maintenance 

of critical components as “substantial maintenance providers” (e.g., landing gear 

repair facilities). 

FAA only directs air carriers to report their top 10 substantial maintenance 

providers. Air carriers formulate this list quarterly according to the number of 

requests for service that repair stations receive rather than the volume of repairs 

they perform. Therefore, the reports can omit high-volume, critical component 

maintenance providers that may have received fewer service requests. For 

example, if four emergency evacuation slides are sent to a repair station 

individually each slide is counted as a separate request. However, 30 emergency 

evacuation slides sent to a repair station at once are counted as 1 service request. 

The provider that only repaired 4 slides would then receive a higher reporting 

priority over the provider that repaired 30 slides. As a result, a high-volume 

substantial maintenance provider would be omitted from the quarterly report just 

on the basis of the shipping method the carrier uses to send its emergency 

evacuation slides to its vendor. 

Our review of air carriers’ reports submitted to FAA confirmed inconsistencies in 

data reporting. For example, some of the reports only included the 

top 10 substantial maintenance providers, as requested by FAA. Others contained 

a mix of both substantial maintenance providers and high-volume, critical 

component vendors, such as those providers that repair wheels and brakes. In our 

view, including high-volume critical components would benefit FAA’s oversight 

efforts. If the reports are to be an effective means for FAA to track and accurately 

target those repair stations that carriers use the most, a more thorough process will 

be needed. 

FAA has initiated the following two actions to improve the reporting of 

outsourced maintenance, but these actions still fall short of providing FAA with 

the data it needs: 

Findings 
4

• On January 24, 2008, FAA issued a change to its Operations Specifications 

guidance that would require air carriers to list all certificated and noncertificated repair stations they use. FAA later cancelled this guidance and is 

now developing a new method to obtain this data because industry 

representatives expressed significant concerns with the undue burden of this 

reporting requirement. 

• By the end of calendar year 2008, FAA plans to issue revised guidance that 

will require air carriers to submit data on the amount or volume of repairs they 

outsource. FAA has determined that it can legally require them to submit this 

data through changes to air carriers’ Operations Specifications, rather than 

through the rulemaking process. FAA is also revising related inspector 

guidance to reflect this change. 

We remain concerned because the revisions, as currently drafted, still do not 

require air carriers to report complete volume data for all repairs of critical 

components or FAA inspectors to validate the data. Without some form of data 

verification, FAA cannot be assured that air carriers have provided accurate and 

complete information. 

FAA’s definition of substantial maintenance does not include all repairs of 

critical components, resulting in inconsistent carrier reports of outsourced 

maintenance. FAA inspection guidance defines substantial maintenance as major 

airframe maintenance checks; significant engine work; major alterations or major 

repairs to airframes, engines, or propellers; emergency equipment repairs; and 

aircraft painting. Yet, this definition does not include components such as landing 

gear even though the safe landing of an aircraft relies on properly maintained 

landing gear—maintenance on such components is critical to the safe operation of 

the aircraft. 

As a result, FAA offices applied inconsistent policies on whether air carriers 

should list landing gear repair facilities as substantial maintenance providers. 

Inspectors for five of the nine air carriers we reviewed considered landing gear to 

be substantial maintenance while the remaining four did not. FAA Flight 

Standards staff advised us that decisions on whether landing gear is considered 

substantial maintenance would depend on the type of work performed. We found 

this can lead to wide disparities in air carriers’ reports of locations performing 

repairs of critical components, which can limit inspectors’ ability to conduct 

adequate risk assessments. 

To illustrate, one air carrier that used a landing gear repair station we visited did 

not consider it to be a substantial maintenance provider. Yet, that repair station 

performed the same work for another air carrier that did consider it to be a 

substantial maintenance provider. As a result, although the former air carrier was 

Findings 
5

the repair station’s biggest customer, with 59 landing gears sent for repair in 2005, 

we found that, at the time of our review, neither the CMO inspectors nor air carrier 

auditors had visited the facility in nearly 4 years. 

Air carriers must correctly and consistently identify repair stations that conduct 

substantial maintenance since FAA inspectors and air carrier auditors target these 

facilities as higher oversight priorities. FAA should reassess its definition of 

substantial maintenance, identify critical components that should be included in 

the definition, and ensure that air carriers and FAA offices consistently apply this 

definition. 

FAA Does Not Have a Policy Governing When Inspectors Should Visit 

Substantial Maintenance Providers 

FAA requires air carriers to have a system in place, called the Continuing Analysis 

and Surveillance (CAS) System, that continually detects and identifies deficiencies 

found at repair stations and provides timely corrective action. Air carriers 

primarily use periodic quality assurance audits to assess whether repair stations are 

properly performing their inspection and maintenance programs. Since 1996, 

FAA has required air carriers to conduct on-site audits before contract repair 

facilities can be used to provide substantial maintenance. 

FAA does not, however, require its CMO inspectors to conduct on-site 

inspections—they can just review air carriers’ pre-contract award audits as a 

basis for approving air carriers’ use of the repair stations. FAA allows 

inspectors to decide when the initial inspections for substantial maintenance 

providers should take place. In addition, FAA has not established a timeframe for 

when inspectors should visit facilities after they are approved as outsourced 

maintenance providers. On-site inspections conducted prior to approval for carrier 

use would provide assurance that the facility does in fact have the proper 

procedures, tooling, training, and equipment to conduct aircraft maintenance in 

accordance with air carriers’ procedures. Without an established policy for 

inspection schedules, there is no standard for all FAA offices regarding initial 

inspector visits, which can cause safety issues to go unchecked at repair stations—

some for as long as 5 years—and limit CMO inspectors’ ability to effectively 

assess risks (see table 2 on page 6). 

For example, CMO inspectors did not inspect one foreign heavy airframe repair 

station until 8 months after FAA granted initial approval—even though IFO 

inspectors responsible for overseeing this facility had found 23 discrepancies 

3 months after the initial approval (during their annual inspection). Some of these 

discrepancies were significant and could have affected the quality of repairs for all 

air carriers using the facility (e.g., there were not enough required tools, required 

Findings 
6

inspections of completed work were not accomplished, and the safekeeping of 

parts in long-term storage could not be guaranteed). By the time CMO inspectors 

visited the facility, it had already performed heavy maintenance checks on five of 

the air carrier’s aircraft. Since CMO inspectors are responsible for ensuring that 

repair stations meet carrier maintenance standards, the IFO inspection findings 

should have prompted more immediate attention from the CMO. The CMO 

inspectors had relied on the air carrier’s audit as a basis for initial approval and 

identified outsourcing risks in their surveillance plan as “unknown” since they had 

not been on site. 

Table 2. Repair Stations That Performed Substantial 

Maintenance for Long Periods Before First CMO Inspection 

Repair Station Number of Aircraft and/or 

Parts Repaired Before 

First FAA Visit/a

Time Lapse Between 

Approval for Carrier Use 

and First FAA Inspection/b

A 5 heavy airframe checks 8 months 

B 7 heavy airframe checks 5 months 

C 39 engines 5 years 

D 30 landing gears a year At least 5 years 

 E/c At least 81 landing gears 

At least 94 landing gears 

At least 21 landing gears 

At least 5 years 

At least 5 years 

At least 5 years a/Repair station and/or air carrier records 

b/Source: FAA inspection database 

c/Three air carriers use this repair station. 

It is important to note the following regarding repair stations C and E: 

• FAA solely relied on a foreign authority to oversee repair station C. 

Although FAA can conduct spot inspections at this repair station, the Agency’s 

IFO inspectors had not conducted any inspections of this facility for over 

5 years at the time of our review. Instead, FAA solely relied on inspectors 

from the foreign aviation authority to inspect this facility and provide FAA 

with a recommendation to renew the facility’s FAA maintenance certificate. 

After we conducted our review at this IFO, FAA inspectors initiated a joint 

inspection with the foreign aviation authority. 

• None of the CMO inspectors for three air carriers that used repair station 

E had inspected the facility. Despite the failure of landing gears that were 

repaired by repair station E, CMO inspectors for the carrier that experienced 

the failures did not inspect the repair station. An internal investigation 

performed by the repair station revealed it had performed an improper repair 

on 24 landing gears for this carrier over a 2-year period. Therefore, no one 

who had reviewed this facility during these 2 years—including FSDO 

Findings 
7

inspectors, air carrier auditors, and repair station internal auditors—detected 

this repair error until the air carrier experienced landing gear problems. 

We identified similar problems with the frequency of CMO inspectors’ on-site 

inspections at repair stations performing work for cargo carriers. For example, 

FAA inspectors for 2 cargo air carriers had not visited a major foreign engine 

overhaul facility in at least 5 years even though the facility repaired 50 engines in 

1 year for those carriers. 

Inspector Staffing and Budget Issues Could Be Affecting FAA’s Ability To 

Provide Sufficient Inspection Coverage for Substantial Maintenance 

Providers

Inspectors at five of the nine air carriers we reviewed told us that staffing and 

budget issues affected their ability to provide sufficient inspection coverage for 

substantial maintenance providers. Inspectors for one of these five were only able 

to inspect 16 percent of the air carrier’s substantial maintenance providers in 2007. 

For example, inspectors stated that they did not have enough on-site time at repair 

stations and that this time was split between aging aircraft inspections and 

outsourced inspections. Since aging aircraft inspections—those inspections 

requiring a visual check of the condition of an aircraft’s structure—are mandated 

by Congress, money is made available to FAA to perform these essential 

inspections. FAA principal inspectors have instructed their inspectors to combine 

contract maintenance inspections with their aging aircraft inspections. Although 

this procedure seems prudent, inspectors told us that they do not have adequate 

time during a typical 2- to 3-day inspection visit to properly assess both programs. 

In addition, FSDO principal maintenance inspectors for two heavy airframe repair 

stations told us that staffing and budget constraints limited their oversight 

capabilities. FAA is addressing these issues by developing a staffing model to 

better determine its staffing needs given the increasing shift to outsourced 

maintenance. 

FAA Relies Heavily on Air Carrier and Repair Station Audits, Which 

Are Not Always Sufficient To Correct Identified Deficiencies 

In addition to their own inspections, FAA inspectors must ensure that air carriers 

and repair stations have strong audit systems to correct identified deficiencies, as 

FAA relies heavily on their oversight. While all the carriers we visited had formal 

audit programs, we found that these audits were not always thorough and that 

FAA should have required its inspectors to perform on-site inspections in some 

instances. Specifically, at 5 of the 15 repair stations we visited we found that air 

carrier auditors did not identify all deficiencies and adequately follow up on 

Findings 
8

findings. FAA and air carriers also rely on repair stations to perform audits of 

external vendors they contract with for parts and maintenance. We determined 

that repair station processes for conducting these audits, correcting identified 

deficiencies, and performing trend analyses could have been stronger at 

10 of the 15 repair stations we visited. Without reliable oversight of audit findings 

and corrective actions, maintenance problems at repair stations can remain 

undetected or reoccur. 

FAA Needs To Ensure Inspectors Visit Heavy Airframe Repair Stations 

Instead of Allowing Them To Solely Rely on Air Carrier Audits 

Our review of FAA inspections of nine air carriers’ CAS programs showed that 

FAA identified problems with three of the nine carriers’ quality assurance audit 

programs—the very audit programs that FAA inspectors can opt to rely on when 

they decide to approve substantial maintenance providers for use. We question 

this oversight practice given the following problems FAA identified: 

• Faulty CAS procedures that could not properly identify weaknesses in vendors’ 

heavy maintenance processes. 

• Inaccurate reporting of findings in audit reports. 

• A lack of regularly scheduled and effective CAS meetings. These meetings are 

important because air carrier representatives discuss data analyses and identify 

high-risk areas that will be closely tracked. 

In addition, FAA cited one of these three air carriers for having inadequate CAS 

program management. This included the following: 

• An undersized quality assurance audit staff. 

• No person designated with the responsibility for overall program management. 

• Sixty corrective action responses from a major repair vendor that exceeded the 

required 10-day response time window. 

These problems, however, did not stop FAA inspectors from relying on the air 

carrier’s audits to approve substantial maintenance providers for use by that 

carrier—without first conducting on-site, pre-award inspections of those facilities. 

For example, CMO inspectors for one air carrier relied on the air carrier’s precontract award audit report to approve the repair station for use. However, when 

CMO inspectors performed an on-site inspection 3 months later—when the first 

aircraft was in for repair—they identified significant findings related to 

mechanics’ training. FAA inspectors required the air carrier to make changes to 

Findings 
9

its training program for contract vendor employees and took enforcement action to 

address the following deficiencies: 

• Over 100 repair station employees did not receive specialized maintenance 

training by the required due date; yet, inspectors found that these employees 

were working on the air carrier’s aircraft. 

• Several repair station employees had not received a required 8-hour air carrier 

training class; instead, air carrier personnel provided a shortened 4.5-hour 

training class, contrary to company manual requirements. 

In this instance, solely relying on the air carrier’s audit to approve the facility for 

use was insufficient. FAA either needs to conduct an on-site inspection before 

approving facilities for use or verify that the air carrier’s audit process is sufficient 

to ensure that repair stations’ mechanics are properly trained and fully understand 

air carrier requirements before they begin working on air carriers’ aircraft. 

Currently, however, FAA relies on air carriers to ensure personnel at repair 

stations are fully trained. FAA guidance to the industry7

 only states that air 

carriers should verify that personnel, including contract maintenance provider 

staff, are trained and qualified to accomplish their duties. At another air carrier we 

reviewed, an aircraft released into service after undergoing a heavy maintenance 

check at a repair station had to turn back following take-off because the nose 

landing gear would not retract. 

In investigating the cause, air carrier officials determined that the repair station 

mechanics had been trained but did not fully understand the air carrier’s 

requirements for landing gear repairs. The air carrier had to conduct an informal 

training session for repair station mechanics using photographs to more clearly 

show how each part is assembled. In this case, if the air carrier had conducted a 

more thorough audit of the repair station it would have found that the personnel 

were improperly trained and the incident may have been avoided. 

FAA Must Ensure Air Carrier Audits Verify Repair Stations’ Corrective 

Actions Before Closing Audit Findings 

When air carrier auditors identify a deficiency, the air carrier must determine if a 

corrective action is warranted and, if so, require the repair station to provide a 

written response detailing the cause of the problem, the corrective action that 

should be taken, the action for preventing recurrence, and an estimated completion 

date. We found, however, that air carriers typically close the findings based on 

projected corrective actions from the repair facility management without ensuring 

7

 Advisory Circular 120-79, Developing and Implementing a Continuing Analysis and Surveillance System, 

April 21, 2003. 

Findings 
10

that the corrective action actually resolves the problem. As a result, identified 

deficiencies reoccur. For example: 

• At a heavy airframe maintenance provider, we identified work cards that air 

carrier mechanics and inspectors had not properly signed, including cards for 

significant maintenance tasks. Without proper sign-offs, there is no assurance 

that the work was actually performed. Air carrier auditors had reported a 

similar finding at this repair station 6 months before our on-site audit, but they 

had closed it without ensuring that the repair station resolved the problem. 

• At a foreign repair station, we observed that temperature and humidity in the 

engine bearing inspection shop were consistently above the maximum allowed 

by the manufacturer. This is critical to safety as engine bearings are precision 

components that support heavy loads at high speed. Air carrier officials had 

identified similar concerns 2 years earlier while conducting an audit initiated 

after an engine shutdown caused by the premature wear of an engine bearing. 

However, air carrier auditors did not return to the facility until almost 2 years 

later. 

We found that the problem was actually occurring as early as September 2002 

(see figure 3 timeline on page 11). Yet, air carrier auditors and FAA inspectors 

did not ensure that the repair station actually corrected this deficiency. Even 

after we informed the IFO inspector of our finding, he did not verify that the 

problem had been corrected. The IFO inspector did not physically inspect the 

bearing room during his visit in March 2006; instead, he took the repair station 

staff’s word that the bearing room was in compliance. 

During an August 2006 follow-up inspection, the IFO inspector found the same 

problem and determined that shop personnel needed to improve compliance 

with temperature and humidity requirements during bearing inspection. 

According to the inspector, the repair station began recording the temperature 

on the router document associated with the bearing undergoing maintenance 

and inspection. Yet, we found no evidence in FAA’s inspection records to 

show that FAA has verified whether this action resolved the problem. 

Findings 
11

Figure 3. Chronology of FAA Inspections at a Repair Station

Effectiveness of Air Carriers’ On-Site Personnel Unknown Due to 

Inconsistencies in the Level of Oversight 

Because FAA cannot continually be on site to inspect repair stations, the Agency 

also relies on another layer of air carrier oversight at heavy airframe maintenance 

providers: on-site air carrier representatives. However, FAA does not have any 

guidance for how these personnel should examine repairs and document 

observations. As a result, this oversight is inconsistent, and the lack of air carrier 

data from these personnel makes it difficult to determine whether this process is 

effective. For example, 

• On-site personnel for two of the nine air carriers we reviewed performed only 

undocumented, on-the-spot inspections of repairs. As a result, these carriers 

did not have methods for ensuring corrective actions or requiring data for trend 

analysis. When we asked to review one of these carrier’s procedures, we were 

told that the procedures did not exist and that there were plans to add a section 

to the procedures manual that would deal strictly with outsourcing, but that had 

not yet occurred. In addition, on-site personnel at this repair station told us 

they only spent 35 percent of the time on the hangar floor. Yet, on-site 

personnel for another air carrier, which has a formal on-site monitoring 

process, at the same facility told us they spent about 70 percent of the time on 

the hangar floor. Both air carriers that used this repair station operate similar 

aircraft and had approximately the same number of aircraft serviced by the 

repair station. 

• The number of on-site air carrier personnel ranged from 3 personnel for 

1 carrier to 22 personnel for another carrier at a different repair station. We 

recognize that there are many variables in determining how many on-site 

personnel air carriers will place at repair stations; however, without any 

guidance, FAA inspectors face difficulties in applying consistent oversight of 

this process. 

After joint CMO/air 

carrier audit, CMO 

recommends improved 

temperature and 

humidity controls in 

bearing room to p

another engine failure. 

Asks IFO inspector 

follow up. 

IFO inspector finds 

repair station 

cannot prove 

compliance with 

temperature and 

humidity 

requirements. 

2002 2004 2005 2006 

IFO visits in Sep. 

and finds 

temperature and 

humidity 

uncontrolled in 

bearing room. 

revent 

to 

IFO inspector 

visits but does 

not inspect 

Source: FAA Inspection Records, Air Carrier Audit Records, and OIG On-Site Visit Records 

Joint CMO/air 

carrier audit finds 

same problem in 

bearing room, but 

CMO does not 

record in database. bearing room. 

IFO inspector 

visits but does 

not follow up on 

CMO’s request 

regarding 

bearing room. 

OIG visit finds 

bearing room 

temperature 

uncontrolled.

Aug

14th –

Sep/Oct Jun Jan Mar

20th

Findings 
12

To improve the air carrier on-site representative process, FAA should develop 

guidance that instructs on-site personnel to record their observations of substantial 

maintenance so that the data are available to FAA inspectors and air carrier 

auditors. 

Repair Stations Need To Improve Quality Assurance Processes

Repair stations’ audit programs must ensure that facilities they use adequately 

correct deficiencies disclosed by their internal and external (vendor and supplier) 

audits. Subcontractors to repair stations are frequently responsible for repairing 

critical parts. We found, however, that repair stations need to improve their 

quality assurance processes. 

For example, a parts receiving inspector at a domestic repair station—not a trained 

quality assurance auditor—performed desk audits of repair station vendors. 

Allowing a person not trained as an auditor to conduct audits raises concerns as to 

the type of in-depth review performed of all current vendors’ documentation and 

the handling of any findings. In 2004, an air carrier also found problems at this 

repair station regarding limited involvement from the quality assurance 

department. Specifically, the carrier was concerned that the quality assurance 

department was not involved in the corrective action process, which resulted in 

recurring deficiencies.

We found the following instance where all three types of oversight systems—

FAA, air carrier, and repair station—failed to detect weaknesses at a heavy 

maintenance provider: 

Two air carrier audits and two FAA inspections (CMO and FSDO) failed to detect 

significant weaknesses in a heavy airframe repair station’s internal audit program. 

These were not discovered until another major air carrier’s pre-contract award 

audit found significant problems in maintenance practices. This brings the quality 

of air carrier and FAA oversight into question, along with the repair station’s 

internal program. The problems identified were so serious that repair station 

management stopped operations for over a month so it could take corrective 

actions. Specifically, the repair station did not properly oversee the following: 

Findings 
13

• Composite shop practices: Numerous problems found, such as mechanics 

using improperly calibrated equipment, which indicated a complete lack of 

control over this critical maintenance process. 

• Subcontractor maintenance: Numerous problems found, such as the use of 

an unqualified subcontracted employee to perform inspections, use of 

unapproved vendors, and assignment of an acceptable rating and approval for a 

vendor despite the vendor’s self-assessment survey being 80 percent 

incomplete. 

• Non-destructive testing processes: Problems found included unqualified 

inspectors performing inspections and required tests not being performed. 

• Internal audit program: Repair station personnel did not identify 

deficiencies during internal audits because their audit checklists were not 

detailed enough to detect these problems. In addition, we found that the person 

conducting the audits and the head of the quality assurance department did not 

have formal audit training or auditor certifications. 

The air carrier that detected these deficiencies ultimately chose not to contract 

with this heavy airframe repair station. Therefore, the responsibility for ensuring 

that the repair station properly addressed these deficiencies, regardless of the 

carrier’s decision, should have fallen to the FSDO inspectors responsible for 

overseeing this repair station. However, our review of FAA’s inspection database 

disclosed that even though repair station officials notified FSDO inspectors of the 

air carrier’s audit findings, FSDO inspectors did not record the audit findings or 

indicate any follow-up inspections. As a result, other CMO inspectors, whose 

assigned air carriers also use this repair station, would not have known about these 

problems, some of which could affect the airworthiness of the aircraft they 

oversee. 

It is critical that inspectors closely review air carrier audit findings; validate, while 

on site, that repair stations corrected deficiencies; and fully document their 

results—especially since FAA has no requirement for when carriers must conduct 

a follow-up audit (a second audit may not occur until 1 to 2 years later). 

Documenting these reviews is important because many air carrier findings identify 

deficiencies within repair stations (including within facilities’ internal audit 

programs) that should be brought to FSDO inspectors’ attention. 

Findings 
14

FAA Needs To Improve Its Inspection Data Documentation 

In 2003, we reported that FAA’s FSDO and CMO inspectors were not sharing 

inspection information. In response, FAA implemented procedures to improve 

information sharing by requiring inspectors to include repair station names on 

inspection reports and document areas inspected, the results, and corrective actions 

taken in the national inspection database. While FAA has improved in this area, 

we found this problem persists among FAA offices. In addition, FAA still has not 

corrected problems with recording the identity of inspected repair stations, which 

we also reported in 2003. 

Our interviews with inspectors and evaluation of inspection records disclosed poor 

communication among 12 of the 19 FAA offices we either contacted or visited. 

We identified the following types of communication problems: 

• Poor interaction between FSDO/IFO and CMO inspectors. 

• Undocumented inspection findings. 

• Limited communication between FAA and foreign authorities. 

• Untimely communication of significant inspection findings. 

As a result, inspectors had incomplete data to prepare risk assessments, and there 

was no assurance that identified deficiencies were adequately corrected. For 

example:

• Deficiencies at a heavy maintenance repair station went uncorrected due to a 

breakdown in communication between FSDO and CMO inspectors and a 

FSDO’s failure to review the inspection database. Specifically, a CMO 

inspector had identified poor conditions in the composite shop at this repair 

station that could cause contamination and affect the integrity of final repairs. 

The CMO inspector recorded his inspection results in the inspection database 

and stated in his report that he had left a voicemail to FSDO inspectors 

responsible for overseeing this facility to advise them of his findings. 

When we showed FSDO inspectors a copy of the inspection record, they told 

us they never knew about these problems even though the problems were 

recorded in the database nearly 4 months earlier. In addition, they told us that 

they did not know the other inspector had tried to contact them. As a result, 

the problems in the composite shop still existed 2 months after the CMO 

inspector first found the problems. 

• CMO inspectors for a major air carrier were unaware of a FSDO inspector’s 

findings regarding a heavy airframe repair station that the carrier used. The 

FSDO inspector found that the repair station had started work on the air 

Findings 
15

carrier’s aircraft before ensuring it had all tools, equipment, and manpower 

required to perform maintenance (i.e., only 30 maintenance personnel were 

available for work performed during shifts that would normally require 

approximately 110). When we questioned the CMO inspectors about this 

finding, they said they were unaware of the finding even though it was 

recorded in FAA’s inspection database. 

• In assessing risks at a domestic repair station, CMO inspectors may have been 

unaware of deficiencies because the FSDO inspector did not document any 

findings in the inspection database. Rather he simply told the repair station to 

fix the discrepancies and then visually checked for corrective actions during 

the next visit. For instance, the repair station made an error that affected 24 air 

carrier nose landing gears repaired over a 2-year period. The error was 

reported to FAA but not entered in the database. This prevented other FAA 

inspectors from accessing key safety data about this repair station. As a result, 

the repair station could receive fewer inspections. This repair station had 

received no on-site monitoring by CMO inspectors for air carriers using this 

facility for at least 5 years. 

• At a foreign repair station, IFO inspectors did not consistently enter inspection 

findings in FAA’s database. As a result, CMO inspectors were not able to 

view these findings and properly assess risk at this foreign repair station where 

their assigned air carrier has contracted maintenance. 

Our review showed that between 2003 and 2005, the foreign aviation authority 

conducted three inspections of this foreign engine repair station on FAA’s 

behalf through international aviation agreements with the United States. The 

inspectors identified 23 findings and reported them to the IFO. FAA recorded 

8 of these 23 findings in the database, but the remaining 15 were only recorded 

on paper copies, which were maintained in the IFO’s files. Although we found 

that most of the 15 findings were administrative in nature, 3 were not. For 

example, inspectors found the following: 

-Weaknesses in the repair station’s knowledge of Part 145 European 

Aviation Safety Agency regulations that govern repair station operations. 

-No evidence to show that internal audit findings conducted by engine repair 

station quality auditors had been completed or closed (a similar finding we 

identified again during our January 2006 visit). 

-No proof of required training. 

Findings 
16

In July 2006, IFO inspectors conducted their own inspection of this engine 

repair station, but they did not record closure actions in the database until we 

asked about the status of the inspection nearly 1 year later. We were told that 

“due to workload and time constraints, the corrective actions were not placed 

into [the database].” 

FAA Needs Procedures To Ensure That Inspectors Properly Identify 

Inspected Repair Stations 

We found that FAA still has not corrected problems with recording the identity of 

inspected repair stations, as we recommended in July 2003. In response, FAA 

issued guidance in April 2005 requiring CMO inspectors to document repair 

station designators on their inspection reports. However, we determined that 

33 percent of the 897 repair station inspection records entered into the database 

after April 2005 and through June 2007 for the air carriers we reviewed did not

contain the required designator information. Moreover, in June 2007, FAA 

reminded all CMO inspectors to include these designators in their reports. FAA 

indicated that failure to do so would hinder analysis capabilities and compromise 

repair station risk models that rely on accurately prepared inspection reports for 

risk assessment. 

Even at this urging, however, inspectors still did not include repair station 

designators. As shown in figure 4, there was virtually no change in inspectors’ 

recordings of repair station designators from May 2005—after FAA issued initial 

guidance—to November 2007—well after FAA issued a reminder to inspectors. 

For the air carriers we reviewed, the percentage of records without designators 

remained approximately one-third of the total records in the database. 

Figure 4. Number of Inspection Reports Without Required 

Repair Station Designator Code 

Figure 4a. Reports Without Designator 

Codes After April 2005 Guidance 

(May 2005–June 2007)

Figure 4b. Reports Without Designator 

Codes After June 2007 Reminder 

(July–November 2007)

293

604

w/ code

w/o code

25

50

w/ code

w/o code

33% 

33% 

67% 

67% 

Source: FAA inspection records 

Findings 
17

Of the 25 records shown in figure 4b, 1 office was responsible for 16 of these 

records (64 percent) that were entered into the inspection database without a repair 

station designator, a clear violation of inspection guidance and a potential 

detriment to FAA’s ability to properly assess repair station risk. A principal CMO 

inspector in this office told us that inspectors are not required to enter the repair 

station designator unless they are performing surveillance on the repair station, not 

when they are performing oversight of the air carrier’s procedures at the repair 

station. This is contrary to FAA’s direction to include repair station certificate 

numbers on inspection reports. 

Properly recording inspection results is now more important than ever since 

FAA’s risk-based system is predicated on using comprehensive inspection data to 

target inspectors to risk areas. To guarantee the viability of this system, FAA will 

need to ensure that FSDO inspectors conduct an appropriate number of inspections 

and record their results in the inspection database. This will allow CMO 

inspectors to better assess risk at their assigned carriers’ repair stations and adjust 

their surveillance as needed. FAA must also develop adequate procedures to 

ensure inspectors document their findings and review the inspection database for 

previous findings. 

Current inspector guidance recommends that inspectors review all available 

inspection records to note any discrepancies found by other inspectors before they 

inspect a repair station. However, we found that inspectors did not always 

perform this review and if they did, they did not normally record it in FAA’s 

inspection database; therefore, we could not verify whether inspectors actually 

completed this action or followed up on prior findings. 

FAA Should Ensure That Air Carriers Have Well-Defined Processes 

and Responsibilities for Outsourced Maintenance 

Current FAA regulations do not provide specific guidance to air carriers regarding 

outsourced maintenance procedures. The regulations only require each air carrier 

to have (1) a program covering maintenance of its aircraft that it or other persons 

(i.e., contract facilities) perform and (2) a system that monitors and analyzes the 

performance and effectiveness of inspection and maintenance programs.8

 

Although the regulations state that repair stations are to follow air carriers’ 

procedures, air carrier manuals have been traditionally geared toward in-house 

maintenance. Since repair stations may perform repairs for various air carriers, all 

with different in-house procedures, FAA should ensure that air carriers provide 

 

8

 14 C.F.R. § Part 121.369 currently requires each air carrier to have a program covering maintenance, preventive 

maintenance, and alterations performed by it or by other persons. This regulation also requires maintenance, 

preventive maintenance, and alterations to be performed in accordance with the air carrier’s manual. 

Findings 
18

repair stations with well-defined maintenance procedures and properly document 

their oversight processes. 

We found key oversight and maintenance processes that FAA should require air 

carriers to document in their manuals, such as vendor reliability programs and 

subcontracting and parts receiving processes. 

FAA Should Encourage Air Carriers To Better Document Programs To 

Track Reliability of Outsourced Maintenance Vendors 

Although not required by FAA, most of the air carriers we reviewed had 

established reliability programs to monitor the effectiveness of aircraft 

maintenance performed by outsourced maintenance vendors. However, we found 

inconsistencies in how air carriers accomplished this monitoring, and some air 

carriers had not fully documented the process in their FAA-approved manual. 

For example, a major air carrier had a system to track maintenance difficulty items 

and aircraft out-of-service rates against every substantial maintenance provider; 

yet, the carrier did not document the system within its policies and procedures, and 

the vendor scoring system did not contain well-defined criteria. A lack of defined 

procedures for scoring vendor performance may not give an accurate view of 

airframe heavy maintenance vendor performance. 

FAA Should Ensure That Air Carriers Clearly Document Processes for 

Approving Vendors and Receiving Parts 

We determined that air carriers had varying degrees of controls for ensuring that 

new parts and parts sent out for repair were from approved vendors and met 

specifications when received. Air carriers often require repair stations to use air 

carrier-approved vendors for supplying new or repaired parts. In addition, repair 

stations have their own approved vendor lists they use if air carriers do not specify 

which vendors to use. This results in multiple approved vendor lists and multiple 

procedures that repair stations must follow to ensure they are using only air carrier 

approved vendors. Another potentially vulnerable area we identified is when air 

carriers have parts sent directly from a vendor without going through its receiving 

process. FAA must ensure air carriers document clearly how these parts should be 

processed.

FAA recognizes the discrepancies within air carriers’ programs for in-house and 

outsourced maintenance. FAA is developing a rule to require specific language in 

air carriers’ manuals for outsourced maintenance. The Agency originally expected 

to issue its proposed rulemaking in June 2008, but it has been delayed by higher 

priority rulemakings. In our view, FAA must initiate interim actions, such as 

Findings 
19

encouraging “Airworthiness Agreements” between air carriers and repair stations 

that clearly define outsourced maintenance responsibilities (e.g., how mechanics’ 

training will be accomplished). 

RECOMMENDATIONS 

We recommend that FAA: 

1. Improve its maintenance data reporting system by: (a) revising its guidance 

to include all maintenance providers performing repairs of critical 

components, not just the top 10 substantial maintenance providers and 

(b) developing procedures for inspectors to validate the accuracy and 

consistency of reports. 

2. Require CMO inspectors to conduct (a) initial baseline inspections of 

substantial maintenance providers to assess whether the maintenance 

providers are in compliance with air carriers’ procedures and (b) follow-up 

inspections to determine whether this baseline assessment has changed. 

3. Reassess its definition of substantial maintenance to include critical 

components and ensure that air carriers and FAA offices consistently apply 

the definition. 

4. Require inspectors to: (a) follow up to verify that deficiencies identified by 

air carriers have been corrected at repair stations and (b) ensure that repair 

stations have adequate processes for conducting audits, correcting identified 

deficiencies, and performing trend analyses of findings. 

5. Develop controls to ensure inspectors are complying with inspector guidance 

to document their findings in FAA’s inspection database and review the 

inspection database for previous findings. 

6. Ensure air carriers document inspections conducted by air carriers’ on-site 

technical representatives at heavy airframe maintenance providers. 

7. Encourage the industry best practice of using airworthiness agreements 

between air carriers and repair stations that more clearly define maintenance 

procedures and responsibilities. 

Recommendations 
20

AGENCY COMMENTS AND OFFICE OF INSPECTOR GENERAL 

RESPONSE 

We provided FAA with our draft report on August 22, 2008, and received FAA’s 

comments on September 26, 2008. FAA concurred with all seven 

recommendations and provided appropriate milestones for implementing 

corrective actions. We consider recommendations 1, 2, 3, 6, and 7 resolved and 

open pending completion of the planned actions. 

However, for recommendations 4 and 5, we are requesting that FAA provide 

additional information since FAA’s response and planned actions do not fully 

address our intent, as discussed below. 

Recommendation 4: While FAA’s planned actions adequately address 

recommendation 4a, its response to 4b requires further clarification. Specifically, 

FAA’s planned actions, if properly implemented, will verify that air carriers have 

adequate audit processes to oversee maintenance performed at repair stations. 

However, it is not clear whether the Agency intends for FAA inspectors and air 

carriers to also verify that repair stations have adequate audit processes for their 

vendors. Therefore, we request that FAA clarify its planned actions with regard to 

recommendation 4b to address oversight of repair stations’ audit processes. 

Recommendation 5: FAA plans to revise ATOS software to make repair station 

designators a required field—an action that complies with recommendations from 

this report and our prior reports. However, we are concerned that FAA’s planned 

action to provide guidance to ATOS data reviewers to include documentation of 

repair station findings in their reviews will not address all the situations that we 

identified during our audit. 

For example, we found inspection documentation problems at FSDOs and IFOs 

that do not have ATOS data reviewers. Therefore, revisions made to ATOS 

processes would not improve these situations. In addition, FAA did not address 

the portion of the recommendation related to establishing controls to ensure 

inspectors review the inspection database for previous findings. We therefore 

request that FAA provide additional information to fully address recommendation 

5. 

Agency Comments and Office of Inspector General Response 
21

Agency Comments and Office of Inspector General Response 

ACTIONS REQUIRED 

FAA’s planned actions satisfy the intent of our recommendations for 

recommendations 1, 2, 3, 6, and 7, and no further information is required. In 

accordance with Department of Transportation 8000.1C, we request that FAA 

provide us with additional information on actions it intends to take to fully address 

recommendations 4b and 5 along with estimated target completion dates. We 

would appreciate receiving your response within 30 calendar days. 
22

EXHIBIT A. SCOPE, METHODOLOGY, AND PRIOR WORK 

We conducted this performance audit between May 2005 and June 2008 in 

accordance with generally accepted Government Auditing Standards prescribed by 

the Comptroller General of the United States. We included such tests as necessary 

to provide reasonable assurance of detecting abuse or illegal acts. In March 2007, 

we testified on our preliminary analysis results before the House Transportation 

and Infrastructure Committee. 

We performed work at FAA Headquarters, 16 FAA field offices, 9 major air 

carriers, and 15 repair stations. We also contacted three other FAA offices to 

obtain data. The nine major air carriers that we reviewed represented a crosssection of nine of the largest network and low-cost air carriers that had either 

always outsourced their maintenance or had recently begun shifting to 

outsourcing. In addition, we met with officials at one additional air carrier, 

American Airlines, and its associated FAA certificate management office to 

determine the carrier’s reason for keeping the majority of its maintenance inhouse. 

To determine which repair stations to visit, we obtained and reviewed the lists of 

approved substantial maintenance providers for the nine air carriers selected for 

review to ascertain which repair stations they use. Our goal was to ensure that we 

established a balanced number of both foreign and domestic repair stations 

coupled with those stations that are used the most by U.S. air carriers. The 

15 repair stations visited all conducted substantial maintenance for air carriers. Of 

the 15, 11 performed heavy airframe maintenance, 2 performed engine overhauls, 

and 2 performed overhauls of landing gear. Exhibit B lists the entities we visited 

or contacted during our audit. 

To determine the type and quantity of maintenance that air carriers are 

outsourcing, we requested data from the nine air carriers visited. Our initial work 

disclosed that obtaining quantities for all types of maintenance would be 

extremely labor-intensive because air carriers did not have the data readily 

available, did not report the data consistently, and in some instances would not 

provide it because of the data’s proprietary nature. Therefore, as agreed to with 

congressional staff, we focused our review and analysis of repair volume on heavy 

airframe maintenance checks because of the critical nature of this work and the 

fact that these data are more readily available at air carriers. 

To assist us in assessing the effectiveness of FAA and air carrier oversight, we 

contracted with Simat, Helliessen and Eichner, Inc. (SH&E), an international air 

transport consulting firm. SH&E focused on determining whether repair station 

Exhibit A. Scope, Methodology, and Prior Work
23

Exhibit A. Scope, Methodology, and Prior Work 

internal quality assurance programs, air carrier quality oversight, and FAA 

surveillance plans were in place and functioning satisfactorily. SH&E also 

conducted random testing of repair station procedures to identify any weaknesses 

in FAA’s oversight. 

Prior OIG Work on Outsourced Maintenance 

• Statement Before the House Transportation and Infrastructure Committee, 

“Aviation Safety: FAA’s Oversight of Outsourced Maintenance Facilities,” 

March 29, 2007 (CC-2007-035). 

• Statement Before the Senate Subcommittee on Aviation Operations, Safety, 

and Security, “Aviation Safety: FAA Oversight of Foreign Repair Stations,” 

June 20, 2007 (CC-2007-076). 

• Review of Air Carriers’ Use of Non-Certificated Repair Facilities, 

December 15, 2005 (AV-2006-031). 

• Congressional Correspondence to Representative Oberstar Regarding FAA 

Actions on Air Carriers’ Use of Aircraft Repair Stations, June 27, 2005 

(CC-2005-035). 

• Review of Air Carriers’ Use of Aircraft Repair Stations, July 8, 2003 

(AV-2003-047). 
24

EXHIBIT B. ENTITIES VISITED OR CONTACTED 

FEDERAL AVIATION ADMINISTRATION

Headquarters: 

Aviation Safety (AVS) Washington, DC 

 Flight Standards Service Washington, DC 

Certificate Management Offices (CMO) for: 

AirTran Airways Orlando, FL 

 Alaska Airlines Seattle, WA 

 **American Airlines Fort Worth, TX 

 America West Airlines Phoenix, AZ 

 Continental Airlines Houston, TX 

 Delta Air Lines College Park, GA 

 JetBlue Airways Garden City, NY 

 Northwest Airlines Bloomington, MN 

 Southwest Airlines Dallas, TX 

 United Airlines Daly City, CA 

∗US Airways Coraopolis, PA 

Flight Standards District Offices (FSDO): 

Albany FSDO Latham, NY 

 Miami FSDO Miami, FL 

Orlando FSDO Orlando, FL 

Seattle FSDO Renton, WA 

 

∗ Contacted only to obtain clarifying data. 

** Conducted on-site visit only to determine reasons for keeping the majority of its maintenance in-house. 

Exhibit B. Entities Visited or Contacted
25

*Indianapolis FSDO Indianapolis, IN 

*Van Nuys FSDO Van Nuys, CA

International Field Offices (IFO): 

Miami IFO Miami, FL 

 Frankfurt IFO Frankfurt, Germany 

 Singapore IFO Singapore 

AIR CARRIERS

AirTran Airways Orlando, FL 

 Alaska Airlines Seattle, WA 

 **American Airlines Tulsa, OK 

 America West Airlines Phoenix, AZ 

 Continental Airlines Houston, TX 

 Delta Air Lines Atlanta, GA 

 JetBlue Airways Forest Hills, NY 

 Northwest Airlines Minneapolis, MN 

 Southwest Airlines Dallas, TX 

 United Airlines San Francisco, CA 

REPAIR STATIONS

 AAR Landing Gear Services Medley, FL 

 Aeroman San Salvador, El Salvador 

Air Canada Technical Services Vancouver,Canada 

AMECO Beijing Beijing, China 

 Avborne Heavy Maintenance Inc. Miami, FL 

 Empire Aero Center Rome, NY 

Exhibit B. Entities Visited or Contacted 
26

GE-Celma Petropolis, Brazil 

Goodrich Aviation Technical Services Everett, WA 

 HAECO Lantau, Hong Kong 

 Hawker-Pacific Aerospace Sun Valley, CA 

 MTU Maintenance Hannover GMBH Langenhagen, Germany 

 PEMCO World Air Services Dothan, AL 

 SASCO Singapore 

 TAECO Xiamen, China 

 TIMCO Lake City, FL 

INDUSTRY & FAA INSPECTOR WORKFORCE REPRESENTATIVES

Aircraft Mechanics Fraternal Association Washington, DC 

Air Carrier Association of America Washington, DC 

Air Transport Association Washington, DC 

International Brotherhood of Teamsters Phoenix, AZ 

Professional Airways Systems Specialists Washington, DC 

 Regional Airline Association Washington, DC 

Transportation Trades Department, AFL-CIO Washington, DC 

Exhibit B. Entities Visited or Contacted 
27

Exhibit C. Major Contributors to This Report 

EXHIBIT C. MAJOR CONTRIBUTORS TO THIS REPORT 

 Name Title 

 

Lou E. Dixon Assistant Inspector General 

for Aviation and Special Program Audits 

 

 Robin Koch Program Director 

 Kevin George Project Manager 

 James Madden Senior Auditor 

 Stefanie McCans Analyst 

 Manuel Ramos Auditor 

 Travis Wiley Analyst 

 Aiesha Gillespie Analyst 

 Andrea Nossaman Writer-Editor 

 

 
28

APPENDIX. AGENCY COMMENTS 

Federal Aviation 

Administration 

Memorandum 

Date: September 26, 2008 

To: Lou E. Dixon, Assistant Inspector General for Aviation and Special Program Audits 

From: Ramesh K. Punwani, Assistant Administrator for Financial Services/CFO 

Prepared by: Anthony Williams, x79000 

Subject: OIG Draft Report: Air Carriers’ Outsourcing of Aircraft Maintenance 

Thank you for the opportunity to review your draft of the subject report. We concur with all 

recommendations contained in the report. The Federal Aviation Administration’s (FAA) planned 

action for addressing each recommendation is stated below. These actions include a requirement for 

air carriers and repair stations to submit quarterly utilization reports of maintenance providers. FAA is 

also developing a rule to specifically address maintenance completed by external repair stations. 

FAA continues to take important steps to move its safety oversight towards a risk-based system. 

OIG Recommendation 1: Improve its maintenance data reporting system by: (a) revising its guidance 

to include all maintenance providers performing repairs of critical components, not just the top 10 

substantial maintenance providers and (b) developing procedures for inspectors to validate the 

accuracy and consistency of reports. 

FAA Response: Concur. The FAA is revising the guidance and including more than just the top 10 

maintenance providers. Principal airworthiness inspectors will be required to validate the accuracy of 

reports through periodic audits. We will complete our action on this recommendation by March 31, 

2009, subsequent to completing our action on recommendation 3, below. 

OIG Recommendation 2: Require CMO inspectors to conduct (a) initial baseline inspections of 

substantial maintenance providers to assess whether the maintenance providers are in compliance with 

air carriers’ procedures and (b) follow-up inspections to determine whether this baseline assessment 

has changed. 

FAA Response: Concur. The FAA does have current guidance which supports this recommendation 

in FAA Order 8900.1, Flight Standards Information Management Systems (FSIMS),” volume 6, 

“Surveillance,” chapter 2, section 41, “Evaluate/Inspect Part 121/129 (N-registered only)/135 (10 or 

more) and 125 Operator’s Outsource Maintenance Organization Facility. Section 41, paragraph 61123, 

states; “The FAA air carrier inspector will evaluate (emphasis added) the outsource maintenance 

Appendix. Agency Comments
29

provider, facility (certificated or non-certificated and other air carrier) to ensure that it has adequate 

housing, equipment, spare parts, technical data, and qualified personnel available to satisfactorily 

complete all contracted maintenance in accordance with (IAW) parts 91K, 121, 125, 129 (N-registered 

only) and 135 (10 or more), and the air carrier or commercial operators program and applicable 

sections of the maintenance manual.” We agree that initial and follow-up on-site inspections of 

essential maintenance providers (see FAA response to recommendation 3, below) should be 

accomplished to the greatest extent practicable and will implement this recommendation after 

assessing its impact on resources based on the definition of “essential maintenance.” We will need to 

complete our definition as outlined in recommendation 3 to determine what the impact will be to 

require initial audits of all air carriers with operations specifications paragraph D091. Action to be 

completed by June 30, 2009, after determining its impact on resources. 

OIG Recommendation 3: Reassess its definition of substantial maintenance to include critical 

components and ensure that air carriers and FAA offices consistently apply the definition. 

FAA Response: Concur. The FAA has a project in-progress to define a single definition for the term 

“substantial maintenance,” “critical,” and “critical parts.” Our current review of Title 14 Code of 

Federal Regulations (14 CFR) has revealed another maintenance activity performance requirement. 

That activity is the Required Inspection Item (RII). The rules governing RII address maintenance, not 

parts, including at least those items of maintenance that could result in a failure, malfunction, or defect 

endangering the safe operation of the airplane, if not performed properly or if improper parts or 

materials are used. 

We will address these previous terms and the RII maintenance by using the term “essential 

Maintenance” in our FAA guidance, as we conduct our review to determine the impact this will have 

on existing policy, guidance, operations specifications D091, and quarterly utilization reporting. 

At the completion of these two reviews, we will update all policy and guidance to reflect the new 

definition. We expect completion by January 31, 2009. 

OIG Recommendation 4: Require inspectors to: (a) follow up to verify that deficiencies identified by 

air carriers have been corrected at repair stations and (b) ensure that repair stations have adequate 

processes for conducting audits, correcting identified deficiencies, and performing trend analyses of 

findings. 

FAA Response: Concur. Regulations make air carriers responsible for parts (a) and (b) of this 

recommendation. Therefore, we will revise guidance to principal airworthiness inspectors to: (a) verify 

that deficiencies identified by air carriers have been corrected at repair stations when conducting the 

Air Transportation Oversight System (ATOS) element performance inspections at those repair 

stations; and (b) make a determination that the air carrier has adequate processes for conducting audits, 

correcting identified deficiencies, and performing trend analyses of findings when conducting ATOS 

design assessments of elements 1.3.7, Outsource Organization, and/or 1.3.11, Continuous Analysis 

and Surveillance. We will complete action on this recommendation by June 30, 2009. 

OIG Recommendation 5: Develop controls to ensure inspectors are complying with inspector 

guidance to document their findings in FAA's inspection database and review the inspection database 

for previous findings. 

FAA Response: Concur. We will provide guidance to ATOS data reviewers to include in their 

reviews documentation of repair station findings and entry of repair station designators. We will 

complete this action by March 31,2009. We will revise ATOS software to make repair station 

Appendix. Agency Comments 
30

Appendix. Agency Comments 

designators a required field where practicable. We will provide a date for completing this action as 

soon as it can be determined based on other priorities for software revisions. 

OIG Recommendation 6: Ensure air carriers document inspections conducted by air carriers’ on-site 

technical representatives at heavy airframe maintenance providers. 

FAA Response: Concur. The FAA believes that existing regulations and FAA guidance address this 

recommendation. Title 14 CFR, sections 121.373 and 135.431, require the air carrier to establish and 

maintain a Continuing Analysis and Surveillance System (CASS). CASS evaluates the performance 

and effectiveness of a carrier’s inspection program, its program covering other maintenance, 

preventive maintenance, and alterations, its process for the correction of any deficiency in those 

programs. This is true regardless of whether those programs are carried out by the certificate holder or 

by another person. CASS is a quality management system for air carriers and commercial operators 

that monitors and analyzes the performance and effectiveness of inspection and maintenance 

programs. 

The FAA views CASS as a continuous, system safety-based, closed-loop cycle of surveillance, 

investigation, data collection, analysis, corrective action, monitoring, and feedback for operators to use 

to continually monitor and correct any deficiencies. The deficiencies described in the OIG report 

should have been noted in the air carriers’ CASS program through the audits conducted by the air 

carrier. CASS functions are built around principles of what is commonly referred to as risk 

management. In CASS, the FAA expects a formal risk management process (system safety) with 

safety and compliance as the top priorities. 

The FAA will publish a notice placing special emphasis on ensuring that the on-site technical 

representative audit findings are documented during performance assessments of element 1.3.7, and 

element 1.3.11. 

The FAA will evaluate the need for a possible “special emphasis” inspection on air carriers’ CASS 

programs and their effectiveness. We expect our evaluation for “special emphasis” to be completed by 

November 2008 and a notice to be issued by March 31, 2009. 

OIG Recommendation 7: Encourage the industry best practice of using airworthiness agreements 

between air carriers and repair stations that more clearly define maintenance procedures and 

responsibilities. 

FAA Response: Concur. The FAA will review existing maintenance agreements and evaluate for best 

practices and determine what guidance needs to be incorporated in FAA Order 8900.1 and/or AC 120-

16, “Air Carrier Maintenance Programs.” We will complete this action by March 31, 2009. 

S:\\ABUIOO\Share\OIG GAO\05-IIAir Carrier Outsourcing.doc:Anthony Williams:September 24, 

2008 
The following pages contain textual versions of the graphs and charts included in this 

document. These pages were not in the original document but have been added here to 

accommodate assistive technology. 
Air Carriers’ Outsourcing of Aircraft Maintenance 

Section 508 Compliant Presentation 

Figure 1. Percentage of Heavy Airframe Maintenance Checks Outsourced for 

Nine Major Air Carriers From 2003 to 2007 

(Year) 2003 1,126 total checks; of this amount, 385 (or 

34 percent) were outsourced. 

(Year) 2004 1,212 total checks; of this amount, 455 (or 

38 percent) were outsourced. 

(Year) 2005 1,163 total checks; of this amount, 662 (or 

57 percent) were outsourced. 

(Year) 2006 1,208 total checks; of this amount, 815 (or 

67 percent) were outsourced. 

(Year) 2007 1,274 total checks; of this amount, 907 (or 

71 percent) were outsourced. 

Source: Air carrier data 

Figure 2. Locations of Repair Stations That Performed Heavy Airframe 

Maintenance for Nine Major Air Carriers in 2007 

Asia 79 repair stations 

Canada 69 repair stations 

Central America 81 repair stations 

Mexico 17 repair stations 

United States 661 repair stations 

Source: Air carrier data 
Table 2. Repair Stations That Performed Substantial Maintenance for Long 

Periods Before First Certificate Management Office Inspection 

Note: In the table below, data on number of aircraft and/or parts repaired before first 

FAA visit were obtained from repair station and/or air carrier records. 

Note: In the table below, data on time lapsed between approval for carrier use and 

first FAA inspection were obtained from FAA inspection database. 

Repair Station A 5 heavy airframe checks 

performed before first FAA 

visit. 

8 months lapsed between 

approval for carrier use and 

first FAA inspection. 

Repair Station B 7 heavy airframe checks 

performed before first FAA 

visit. 

5 months lapsed between 

approval for carrier use and 

first FAA inspection. 

Repair Station C 39 engines repair before first 

FAA visit. 

5 years lapsed between 

approval for carrier use and 

first FAA inspection. 

Repair Station D 30 landing gears a year 

repaired before first FAA 

visit. 

At least 5 years lapsed between 

approval for carrier use and 

first FAA inspection. 

Repair Station E (Note: 3 

air carriers use this repair 

station)

At least 81 landing gears for 

one carrier repaired before 

first FAA visit. 

At least 5 years lapsed between 

approval for carrier use and 

first FAA inspection. 

Repair Station E At least 94 landing gears for 

one carrier repaired before 

first FAA visit. 

At least 5 years lapsed between 

approval for carrier use and 

first FAA inspection. 

Repair Station E At least 21 landing gears for 

one carrier repaired before 

first FAA visit. 

At least 5 years lapsed between 

approval for carrier use and 

first FAA inspection. 
Figure 3. Chronology of FAA Inspections at a Repair Station 

• 2002: International Field Office visits in September and finds temperature and 

humidity uncontrolled in bearing room. 

• September to October of 2004: After joint Certificate Management Office and air 

carrier audit, Certificate Management Office recommends improved temperature 

and humidity controls in bearing room to prevent another engine failure. Asks 

International Field Office inspector to follow up.

• June 2005: International Field Office inspector visits but does not follow up on 

Certificate Management Office’s request regarding bearing room.

• January 2006: Office of Inspector General visit finds bearing room temperature 

uncontrolled.

• March 14th through March 20th of 2006: Joint Certificate Management Office and 

air carrier audit finds same problem in bearing room, but Certificate Management 

Office does not record in database. International Field Office inspector visits but 

does not inspect bearing room.

• August 2006: International Field Office inspector finds repair station cannot 

prove compliance with temperature and humidity requirements.

Source: FAA Inspection Records, Air Carrier Audit Records, and Office of Inspector 

General On-Site Visit Records 
Figure 4. Number of Inspection Reports Without Required Repair Station 

Designator Code 

Figure 4a. Reports Without Designator Codes After April 2005 Guidance 

(May 2005 to June 2007) 

Number of Inspection Reports With 

Designator Code 

604, or 67 percent 

Number of Inspection Reports Without 

Designator Code 

293, or 33 percent 

Figure 4b. Reports Without Designator Codes After June 2007 Reminder 

(July–November 2007) 

Number of Inspection Reports With 

Designator Code 

50, or 67 percent 

Number of Inspection Reports Without 

Designator Code 

25, or 33 percent 

Source: FAA inspection records