Advisory Circular (AC)

Flight Test Considerations For The Approval Of The Design Of Aircraft Modifications

File No.	5009-6-513	AC No.	513-003
RDIMS No.	528350-V3	Issue No.	01
Issuing Branch	Aircraft Certification	Effective Date	2004-12-01

1.0 Introduction

1.1 Purpose
1.2 Guidance Applicability
1.3 Description of Changes
1.4 Termination

2.0 References

2.1 Reference Document
2.2 Cancelled Document

3.0 Background and Discussion

4.0 Flight Test

4.1 General
4.2 Flight Characteristics
4.3 Performance
4.4 Flight Deck Design
4.5 Flight Guidance
4.6 Navigation Systems
4.7 System Operation
4.8 Aeroplane or Rotorcraft Flight Manual Changes

5.0 Flight Test Techniques

6.0 Request For Additional Information

7.0 Headquarters Contact

1.0 Introduction

1.1 Purpose

The purpose of this Advisory Circular (AC) is to provide general guidance on the flight test considerations associated with the approval of the design of aircraft modifications

1.2 Guidance Applicability

This document is applicable to all Transport Canada personnel, delegates and industry.

1.3 Description of Changes

This document, formerly AMA No. 513.05/1, is reissued as an AC. With the exception of minor editorial changes, the content is unaltered.

1.4 Termination

This document does not have a terminating action. It will however, be reviewed periodically for suitability of content.

2.0 References

2.1 Reference Document

It is intended that the following reference material be used in conjunction with this document:

Chapter 513 of the Airworthiness Manual (AWM), paragraph 513.05(1)(d) - Approval of Modification and Repair Designs, Obligations of an Applicant.

2.2 Cancelled Document

As of the effective date of this document, AMA No. 513.05/1 dated 10 June 2003 is cancelled.

3.0 Background and Discussion

Chapter 513 of the Airworthiness Manual (AWM) contains procedures for the approval of the design of an aircraft modification. To show that the modified aircraft meets the applicable airworthiness standards, flight tests may be required to demonstrate compliance with standards of airworthiness or to determine that the characteristics of the aircraft are not degraded to an unacceptable level. Some examples of design changes which would require flight-testing are set out in the following sections.

4.0 Flight Test

4.1 General

Flight test assessments are usually required for aircraft modifications that could affect airworthiness in areas such as:

(a) Flight Characteristics;

(b) Performance;

(d) Flight Guidance;

(e) Navigation Performance;

(f) System Operation; and

(g) Aeroplane or Rotorcraft Flight Manual changes.

4.2 Flight Characteristics

Flight tests are normally required when a modification may affect aircraft flight characteristics including the following:

(a) controllability and manoeuvrability;

(b) trim;

(d) stalls;

(e) spinning (where applicable);

(f) ground or water handling characteristics; and

(g) miscellaneous flight requirements (vibration and buffeting, high speed characteristics and out-of-trim characteristics).

Some modifications in which flight characteristics are affected include:

(a) changes to the primary or secondary control surface size, surface travel limits, surface actuation systems or balance mechanisms;

(b) powerplant changes affecting the thrust or power level, thrust line, nacelles, pylons, thrust reverser system, propeller or rotor;

(c) the addition of, or change to, fairings, radomes, finlets, antennae, cargo pods, aerial spray equipment or other externally mounted equipment;

(d) increase in the maximum take-off weight or maximum landing weight; and

(e) extension of the forward or aft CG limit.

4.3 Performance

Flight tests are normally required when a modification has some effect on the aircraft lift, drag, installed thrust, maximum weight, ground friction characteristics or braking effectiveness. The effect of the modification on the aircraft performance must be determined in the following areas:

(a) stall speeds;

(b) installed power or thrust;

(d) take-off and landing distances;

(e) accelerate-stop distances;

(f) take-off, approach and landing climb performance;

(g) airspeed indicator position error;

(h) altimeter position error;

(i) helicopter hover performance (IGE and OGE); and

(j) helicopter climb performance.

Examples of modifications which will normally require flight testing because of the impact on performance include:

(a) new or revised take-off or landing flap settings;

(b) externally mounted equipment;

(d) engine nacelle, engine intake, or pylon changes affecting installed thrust;

(e) tire, brake, anti-skid and aerodynamic lift dump systems affecting deceleration performance;

(f) externally mounted equipment which may influence the pitot-static system position errors; and

(g) changes to the pitot static system installation.

4.4 Flight Deck Design

Modifications affecting pilot compartment view, aircraft flight instruments, flight controls, powerplant instruments, warning and caution panels, system controls and displays and pilot workload normally require a flight test assessment.

Some examples include the modification to or addition of:

(a) radios or avionic systems;

(b) head-up displays (HUD);

(d) electronic engine instrument displays;

(e) instruments or controls;

(f) flight crewmember seats, including alternate pilot seat operations;

(g) instruments or equipment affecting pilot compartment view;

(h) lighting systems;

(i) bubble windows; and

(j) helicopter hoisting, hook controls and release systems.

4.5 Flight Guidance

Modification of hardware or software in automatic flight control systems, auto-thrust, auto-brake or auto-land systems and flight director systems may require a flight test assessment. The requirement for flight test can only be determined after a comprehensive analysis is conducted to identify the effect of the modification on all other systems interfacing with the modified component.

Some examples of flight guidance system modifications which may require flight testing include software or hardware changes which affect:

(a) the pitch, yaw or roll rate commanded by the system;

(b) the airspeed at which control laws are phased in and out;

(d) the limits for control surface deflections;

(e) the limits for engagement and disengagement of autopilot, auto-thrust, auto-brake and auto-land systems;

(f) new technology digital systems; and

(g) actuator travel changes and hard-over characteristics.

Since the examples provided in 4.5 cannot be comprehensive, a flight evaluation becomes necessary when a modification made to the flight guidance equipment is likely to change the aircraft characteristics in the normal or failure modes in any approved configuration.

4.6 Navigation Systems

tests to establish system accuracy and performance in order to demonstrate that the modified equipment performs its intended function and that the aircraft will operate satisfactorily using the installed equipment. Systems include ADF, VOR, INS, Omega, Loran, Doppler, Tacan, Satellite Navigation and for the purpose of this advisory, precision navigation and guidance systems such as ILS, MLS and TCAS.

Examples of the modifications which can affect navigation system performance and accuracy include:

(a) addition of externally mounted equipment which may partially obscure a transmitter, antenna, sensor or receiver;

(b) the relocation of antennae, transmitter and receiving sensors;

(d) electrical modifications or the addition of systems which may cause electromagnetic interference with the existing navigation systems; and

(e) a software or hardware update to permit Cat II or steep approaches or both.

4.7 System Operation

Flight tests may be required after modification of any aircraft system not previously discussed. When considering the need for flight tests the failure cases should be assessed to the level where the failure is assumed to occur after dispatch of the aircraft with systems inoperative as permitted in the Master Minimum Equipment List.

Examples of modified systems which may need to be assessed through a flight test program include:

(a) air conditioning and pressurisation systems;

(b) communication systems;

(d) electrical power systems;

(e) fire protection systems;

(f) fuel systems (including engine fuel and control);

(g) hydraulic systems;

(h) ice and rain protection systems;

(i) landing gear;

(j) lighting systems (internal and external);

(k) oxygen systems;

(l) pneumatic systems; and

(m) airborne auxiliary power systems.

In most cases the primary objectives of the flight test assessment of the modified system are:

(a) to confirm that the modified system performs its intended function and has satisfactory operating characteristics;

(b) to confirm that the modified system does not interfere with the function of other aircraft systems; and

(c) to ensure that appropriate procedures are documented for the new equipment as well as any changes to the procedures for other aircraft systems.

4.8 Aeroplane or Rotorcraft Flight Manual Changes

The flight manual usually (but not always) needs to be amended as part of a modification approval. Typically, a supplement is produced results from the modification. AC 513.05/2 provides additional guidance on the format and content of the flight manual supplement.

A flight manual supplement, flight manual amendment or new flight manual is required if one or more of the following conditions are met:

(a) flight testing has shown that operating limitations for the modified aircraft are changed. Examples of this category are:

(i) reduction in maximum operating airspeeds;

(ii) changes to the weight or CG envelope;

(iii) changes to engine operating limitations;

(iv) reduction in maximum operating altitude;

(v) the modified aircraft can only be operated in a restricted role, i.e. day VFR, no icing, etc; and

(vi) changes to system limitations, e.g. minimum autopilot engage altitude is increased.

(b) flight testing has shown, or system changes have necessitated changes to normal, abnormal, or emergency procedures; or

(i) pitot static systems calibrations;

(ii) stall speeds;

(iii) take-off or landing performance or both; and

(iv) climb performance.

5.0 Flight Test Techniques

Many of the flight test techniques recommended for determining compliance with the certification basis of the aircraft are described in various FAA Advisory Circulars (AC) as outlined below, or later revisions thereof:

(a) AC 23-8A Chg. 1 (08-30-93) Flight Test Guide for Certification of Part 23 Airplanes.

(b) AC 25-7A (03-31-98) Flight Test Guide for Certification of Transport Category Airplanes.

(d) AC 29-2B (07-30-97) Certification of Transport Category Rotorcraft.

Guidance for the flight test instrumentation requirements, manoeuvres and data reduction methods is also provided in the above mentioned advisories.

In addition to the FAA ACs several ACs have been published to provide flight test guidance for some specific tests. These ACs normally relate to the airworthiness manual applicable to the type of aircraft under consideration, e.g. (AC 525/1 refers to stall testing on a transport category fixed wing aircraft). These ACs are listed in AC 500/00 of this Manual.

6.0 Request For Additional Information

It is recommended that the Transport Canada Regional Aircraft Certification office be contacted to determine the acceptability and completeness of the proposed tests prior to conducting the flight test. TCCA may need to conduct a flight test assessment of the modified aircraft, so early notification is recommended.

The following address can be used for inquiries:

Transport Canada
Place de Ville
Ottawa, Ontario
K1A 0N8
Attention: Chief, Flight Test (AARDC)
Phone: (613) 952-4315
Fax: (613) 996-9178

7.0 Headquarters Contact

For more information please contact:

Policy Standards Coordinator (AARDH/P)
Phone: (613) 990-3923
Facsimile: (613) 996-9178
E-mail: AARDH-P@tc.gc.ca

Original signed by Maher Khouzam

Maher Khouzam
Chief, Regulatory Standards
Aircraft Certification Branch

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