Aircraft Certification Staff Instruction (ACSI)

ACSI No.: 20
Issue No.:  1
Issue Date:  1988-12-08
AARD File:  5009-3-20

Aircraft Certification Staff Instruction (ACSI)


Table of Contents


1.1 Existing Approvals
1.2 Basis for Approvals
1.3 Evaluation Process



3.1 Requirements of Application
3.2 Processing of Application
3.3 Conditions for Making Approval
3.4 Recording of Approval
3.5 Approval Updates


4.1 Requirements of Application
4.2 Processing of Approval
4.3 Conditions for Making Approval


5.1 General
5.2 Conditions and Means for Cancellation
5.3 Airworthiness Directives
5.4 Modifications other than AD's



7.1 Regulations
7.2 Applications

Appendix A - EROPS Approval Functions and Responsibilities


1.1 Existing Approvals

Since 1985, extended range operations have been an accomplished fact. The Airworthiness Authorities of the USA, France and Canada have granted design and operational approvals based upon AC120-42 or TP6327.

Type design approvals have been granted by the FAA for Boeing 737, 757 and 767 aircraft and operational approvals granted (by exemptions to 60 minute limitations) to American, Pan Am, Aloha and Piedmont Airlines. With the assistance of the DGAC, some airlines operating Airbus aircraft have also obtained EROPS approval from their local Airworthiness Authority.

In Canada, Air Canada has operated B767's on the North Atlantic route and their approval has been based upon TP6327.

1.2 Basis for Approval

To consolidate type design and operational approvals in a single document, TP6327 was created by TCAG in consultation with the FAA. Early drafts, of the FAA's basis, AC120-42, and TCAG's basis, TP6327 were compared and brought into line as far as possible.

The intent of these documents is to identify criteria that must be met to enable EROPS and ensure that the operations are at least as safe as similar operation with 3 or 4 engined aircraft. These documents are precedent setting in that they demand a demonstrated level of operational reliability of the propulsion system and documented prior experience in operating the type, or a closely similar type, by the applicant airline.

prerequisite in service experience and continuing surveillance requirements as specified in Chapters 2, 3, 4 and 5.

1.3 Evaluation Process

In making the existing EROPS approval, evaluations have been accomplished in three major areas:

Engineering, to assure proper type approval and maintenance of the approved aircraft through initial evaluation and periodic update.

Maintenance, to assure that the airline maintenance programs are adequate to preserve the approved configurations and ensure the type approved aircraft is adequately maintained and the EROPS objectives achieved.

Operations, to assure that operational procedures and the operating environment are adequate to maintain extended range safety.


This ASI is directed towards the first two of the three major areas. The third is addressed by personnel from outside the airworthiness organizations at Headquarters and the Regions.

The purpose of the ASI is to indicate the responsibilities and procedures necessary for processing EROPS approvals in response to applications from aircraft manufacturers and operators.


3.1 Requirements

Each application for EROPS approval is expected to include the following:

3.1.1 Aircraft EROPS configuration definition.

3.1.2 Maintenance documentation, where EROPS is different from basic aircraft.

3.1.3 Flight Manual, where EROPS procedures and performance are included.

3.1.4 Master MEL, considering EROPS.

3.1.5 Documented fleet experience.

3.2 Processing of Application

The responsibilities and the required action by Divisions within the Airworthiness Branch and by Regional offices are summarized in the diagram attached to this ASI as Appendix A.

It may be anticipated that an application from an aircraft manufacturer for EROPS approval will come as part of a Type Approval application or as an addition to a Type Approval already issued. For items 3.1.1 through 3.1.4 the coordination and review responsibilities shown in Appendix A are the same as for a non EROPS Type Approval or Type Approval re-issue. These items will be coordinated within the Branch and reviewed in a manner similar to present Type Approval, Validation or Familiarization activities. This ASI does not change the established roles and responsibilities for program coordination and content.

Because TP6327 is not identical to the FAA AC 120-42 care should be exercised in reviewing documentation and it should be noted that some EROPS approvals have been issued using neither document.

Item 3.1.5, substantiating data will normally be submitted by the applicant at the time of application. Engineering Division (ABE) will review this data and use the data generated by the Propulsion System Reliability Assessment Board (PSRAB) of the Exporting Airworthiness Authority (EAA) to make finding of acceptance or otherwise. This findings is facilitated by ABE participation in the PSRAB.

For domestic aircraft, it will be necessary to form a DAB Reliability Board, in accordance with TP6327 and ASI#60, to accomplish the review.

3.3 Conditions for Making Approval

Items 3.1.1 through 3.1.5 must be accepted by the responsible Divisions as being in compliance with or otherwise meeting the requirements of TP6327. The OPI will require notification by the OTI's of this acceptance prior to recording on the Aircraft Type Approval that the type design in question is eligible for EROPS.

3.4 Recording of Approval

Airworthiness type design approval for EROPS will be recorded on the Aircraft Type Approval in the form of a note. It will be necessary to signify to flight crews that such an approval has been granted. This is normally accomplished by the manufacturer annotating the Flight Manual listing EROPS under the kinds of operation for which the aircraft is approved.

The following is an example of a type approval note used to record EROPS type design approval:

"The type design, and performance of this aeroplane have been evaluated and found to comply with the criteria of TP6327. When configured, maintained and operated in accordance with - (insert applicant source document identifier) - the - (insert aircraft type designation) is eligible for EROPS by a Canadian operator. This eligibility does not constitute operational approval for EROPS.

3.5 Approval Updates

Changes in aircraft configuration may take place as the result of product improvement, AD action and PSRAB findings. Those changes which affect EROPS will be incorporated in the configuration document (item 3.1.1) necessitating the periodic review by appropriate OTI's for continued compliance with TP6327. At the time of initial EROPS approval, the Type Approval holder should be informed that since the EROPS type definition is part of the initial approval process, continued validity of his EROPS approval will be contingent upon his informing the Branch (OPI) of all and any configuration changes.


4.1 Requirements of Application

Each application for EROPS is expected to include the following:

4.1.1 Descriptions of the program which will ensure the EROPS aircraft are configured in accordance with the definition against which the EROPS type design approval has been granted.

4.1.2 The approved reliability program, which will show the level of reliability demonstrated by the propulsion systems on EROPS configured aircraft.

4.1.3 The approved maintenance program.

4.1.4 Compiled data which shows that the operator has satisfactory experience in maintaining and operating the aircraft type in compliance with the prerequisite experience requirement of TP6327.

4.2 Processing of Approval

Items 4.1.1 through 4.1.4 are either incorporated in or added to an application for operational approval received at the Regional Office responsible for the applicant Company and will be processed as usual except that:

Items 4.1.1, 4.1.2, and 4.1.3, for EROPS special measures addressing the propulsion system and other EROPS significant equipment are anticipated. The propulsion system reliability program is especially important. In most cases individual Air Carriers will not have sufficient operational hours to give rise to a statistically significant number of occurrences. It is therefore necessary to consider the individual operator in the context of the world fleet. This is accomplished through liaison with the Exporting Airworthiness Authority (EAA) and necessitates some commonality in the reliability data recovery and processing.

4.3 Conditions for Making Approval

The operator applicant will submit data substantiating compliance with TP6327 and it will be reviewed by the responsible Region and ABE. This joint review is an EROPS entry condition following approval. The normal regional surveillance activity is applicable to the carrier's current operation.

When processing an initial application for EROPS, in addition to the normal review at the Regional Office, the applicant's propulsion system reliability program should be referred to ABE for acceptance. The program will be expected to contain a monthly report of propulsion system reliability for submission to ABE. Acceptance by ABE of the reliability program will be a prerequisite for the initial regional approval of EROPS operation.

The prerequisite operator experience demanded by TP6327 is a requirement which separates an EROPS approval process from those previously issued by TCAG. Compliance with items 4.1.4 or 3.1.5 represent the first time operational and type design approvals have been dependent upon previous experience.


5.1 General

The foregoing describes how EROPS approvals may be accomplished and shows that such an approval is dependent upon:

Type design compliance with TP6327. Fleet experience - World wide. Airline configuration control and aircraft maintenance. Prerequisite experience for operation. Demonstrated propulsion system reliability.

Continued compliance and conformity with the established criteria in all these areas is required to keep EROPS approvals in place.

5.2 Condition and Means for Cancellation

Item 5.1.1. Once a finding of type design approval for EROPS has been recorded then only those aircraft in conformity with the EROPS type definition are eligible for EROPS.

Item 5.1.2. During review of the manufacturer's application for type design approval for EROPS, the world fleet operational data will be reviewed. The manufacturer will be required to maintain that data up to date. Should propulsion system reliability show that the criteria of TP6327 are not met, the Director, Airworthiness Branch (DAB) will rescind the type design approval.

Item 5.1.3. Aspects of aircraft configuration management and aircraft maintenance management which are not EROPS specific may impact overall aircraft reliability. It may therefore be necessary to remove special operating privileges, such as EROPS where airline practices are not in accordance with acceptable standards. It may be anticipated that such removals would be accomplished through temporary restrictions applied to the Company's Operations. Coordination between Region, Headquarters Airworthiness and Operations is required.

Item 5.1.4. Where the company reliability program reports indicate that world fleet data and data approved as the airlines prerequisite experience are not applicable, then EROPS operational privileges may be removed by special restrictions.

5.3 Airworthiness Directives

Where Airworthiness Directives are issued which apply to propulsion system of an EROPS aircraft, because of higher reliability targets, it may be necessary to make shorter compliance times mandatory. This will be accomplished through DAB's reissue of the AD, such action will be substantiated through PSRAB findings.

5.4 Modifications other than AD's

A category of modifications exists which, whilst non mandatory for normal operations, are necessary to maintain the propulsion system at a high level of reliability. These modifications will be considered by the PSRAB of the Airworthiness Authority responsible for the original ATA of the affected aircraft and the manufacturer required to add the modifications to the EROPS configuration definition document where necessary. By this means, a modification not subject to an AD may be mandatory for EROPS.


See Appendix A.


7.1 Regulations

As it presently exists TP6327 was written to provide a basis for approval of anticipated applications for EROPS by Air Canada. The policy initiated in 1983 by TCAG's Administrators Office to seek means to approve EROPS and the impending applications required that an interim document be published. As a result, the existing TP document contains regulatory and advisory material covering design, reliability, maintenance and operational criteria. The document resulted from consultation with FAA and CAA whose ETOPS documents (AC 120-42 and CAP 517) are compatible with TP6327.

It is the intent of DAB to incorporate the various criteria of TP6327 in the applicable ANO's, Airworthiness Manual Chapters, and AMA's. Until that is accomplished ABE - Powerplants has been designated OPI to coordinate revisions and updates to TP6327.

7.2 Applications

The Airworthiness Authorities who have been involved in drafting EROPS approval requirements and in granting approvals have done so with their attention focused upon the present generation of twin engined aircraft. These include aircraft such as the B767, B757 and Airbus A300 and derivatives. There are clearly other aircraft that have the potential for extended range applications. Also, there are cases where 3 and 4 engined aircraft fall short of suitable systems and operational criteria for extended diversions under degraded operating conditions.

Airlines operating in a maritime environment or in sparsely settled Regions have found means in the past to obtain approvals for EROPS and to operate safely, using aircraft very different from current wide-bodied twins. Airlines have operated out of New Zealand and Australia to south pacific islands using B737, and Canadian Northern operations with turboprop twins are two good examples where EROPS has been accomplished for some time using deviations or special regulations as the means for approval.

It may be anticipated that EROPS applications for DC-9, 737, BAC 111 and other earlier transport category aircraft, will be received. The basis for approval identified in TP6327 is considered equally applicable to all aircraft in the Transport Category. It is not intended to limit EROPS approvals to latest generation aircraft (767, A310, etc) but to aircraft which meet the criteria. The owners and operators of these aircraft may be expected to include smaller, less sophisticated airlines. Therefore, the prerequisite experience and reliability criteria may be somewhat more arduous for them. However, the FAA, the CAA and Transport Canada basis for approval do not consider that the criteria will change to ease the EROPS entry requirements. The requirements may develop in a direction that allows greater diversion times and more flexible route structures.

Orignal signed by:

James A. Torck
Director, Airworthiness Branch

Appendix A

1. Programs Engineering/Flt.test 1. Programs accept Airworthiness 1. Coordinate Review a/c for
compliance with


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